Fix warnings

Replace try_smtp macro with more resilient method
Drop ref syntax
2024-03-19 16:21:10 +01:00 · 2024-03-19 16:21:10 +01:00 · 2024-03-10 15:28:54 +01:00 · 2024-03-10 15:28:54 +01:00
44 changed files with 1378 additions and 2161 deletions
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,16 +13,16 @@ env:
 jobs:
  rustfmt:
-    name: rustfmt / nightly-2024-09-01
+    name: rustfmt / nightly-2023-06-22
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v2
      - name: Install rust
        run: |
-          rustup default nightly-2024-09-01
+          rustup default nightly-2023-06-22
          rustup component add rustfmt
      - name: cargo fmt
@@ -34,7 +34,7 @@ jobs:
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v2
      - name: Install rust
        run: |
@@ -50,7 +50,7 @@ jobs:
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v2
      - name: Install rust
        run: rustup update --no-self-update stable
@@ -75,12 +75,12 @@ jobs:
            rust: stable
          - name: beta
            rust: beta
-          - name: '1.71'
+          - name: '1.70'
-            rust: '1.71'
+            rust: '1.70'
    steps:
      - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v2
      - name: Install rust
        run: |
@@ -112,6 +112,12 @@ jobs:
      - name: Install dkimverify
        run: sudo apt -y install python3-dkim
      - name: Work around early dependencies MSRV bump
        run: |
          cargo update -p anstyle --precise 1.0.2
          cargo update -p clap --precise 4.3.24
          cargo update -p clap_lex --precise 0.5.0
      - name: Test with no default features
        run: cargo test --no-default-features
@@ -128,7 +134,7 @@ jobs:
 #    name: Coverage
 #    runs-on: ubuntu-latest
 #    steps:
-#      - uses: actions/checkout@v4
+#      - uses: actions/checkout@v2
 #      - uses: actions-rs/toolchain@v1
 #        with:
 #          toolchain: nightly
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,159 +1,3 @@
 <a name="v0.11.12"></a>
 ### v0.11.12 (2025-02-02)
 #### Misc
 * Warn against manually configuring `port` and `tls` on SMTP transport builder ([#1014])
 * Document variants of `Tls` enum ([#1015])
 * Fix rustdoc warnings ([#1016])
 * Add `ContentType::TEXT_PLAIN` to `Message` builder examples ([#1017])
 * Document `SmtpTransport` and `AsyncSmtpTransport` ([#1018])
 * Fix typo in transport builder `credentials` method ([#1019])
 * Document required system dependencies for OpenSSL ([#1030])
 * Improve docs for the `transport::smtp` module ([#1031])
 * Improve docs for smtp transport builder `from_url` ([#1032])
 * Replace `assert!` with `?` on `send` examples ([#1033])
 * Warn on more pedantic clippy lints and fix them ([#1035], [#1036])
 [#1014]: https://github.com/lettre/lettre/pull/1014
 [#1015]: https://github.com/lettre/lettre/pull/1015
 [#1016]: https://github.com/lettre/lettre/pull/1016
 [#1017]: https://github.com/lettre/lettre/pull/1017
 [#1018]: https://github.com/lettre/lettre/pull/1018
 [#1019]: https://github.com/lettre/lettre/pull/1019
 [#1030]: https://github.com/lettre/lettre/pull/1030
 [#1031]: https://github.com/lettre/lettre/pull/1031
 [#1032]: https://github.com/lettre/lettre/pull/1032
 [#1033]: https://github.com/lettre/lettre/pull/1033
 [#1035]: https://github.com/lettre/lettre/pull/1035
 [#1036]: https://github.com/lettre/lettre/pull/1036
 <a name="v0.11.11"></a>
 ### v0.11.11 (2024-12-05)
 #### Upgrade notes
 * MSRV is now 1.71 ([#1008])
 #### Bug fixes
 * Fix off-by-one error reaching the minimum number of configured pooled connections ([#1012])
 #### Misc
 * Fix clippy warnings ([#1009])
 * Fix `-Zminimal-versions` build ([#1007])
 [#1007]: https://github.com/lettre/lettre/pull/1007
 [#1008]: https://github.com/lettre/lettre/pull/1008
 [#1009]: https://github.com/lettre/lettre/pull/1009
 [#1012]: https://github.com/lettre/lettre/pull/1012
 <a name="v0.11.10"></a>
 ### v0.11.10 (2024-10-23)
 #### Bug fixes
 * Ignore disconnect errors when `pool` feature of SMTP transport is disabled ([#999])
 * Use case insensitive comparisons for matching login challenge requests ([#1000])
 [#999]: https://github.com/lettre/lettre/pull/999
 [#1000]: https://github.com/lettre/lettre/pull/1000
 <a name="v0.11.9"></a>
 ### v0.11.9 (2024-09-13)
 #### Bug fixes
 * Fix feature gate for `accept_invalid_hostnames` for rustls ([#988])
 * Fix parsing `Mailbox` with trailing spaces ([#986])
 #### Misc
 * Bump `rustls-native-certs` to v0.8 ([#992])
 * Make getting started example in readme complete ([#990])
 [#988]: https://github.com/lettre/lettre/pull/988
 [#986]: https://github.com/lettre/lettre/pull/986
 [#990]: https://github.com/lettre/lettre/pull/990
 [#992]: https://github.com/lettre/lettre/pull/992
 <a name="v0.11.8"></a>
 ### v0.11.8 (2024-09-03)
 #### Features
 * Add mTLS support ([#974])
 * Implement `accept_invalid_hostnames` for rustls ([#977])
 * Provide certificate chain for peer certificates when using `rustls` or `boring-tls` ([#976])
 #### Changes
 * Make `HeaderName` comparisons via `PartialEq` case insensitive ([#980])
 #### Misc
 * Fix clippy warnings ([#979])
 * Replace manual impl of `#[non_exhaustive]` for `InvalidHeaderName` ([#981])
 [#974]: https://github.com/lettre/lettre/pull/974
 [#976]: https://github.com/lettre/lettre/pull/976
 [#977]: https://github.com/lettre/lettre/pull/977
 [#980]: https://github.com/lettre/lettre/pull/980
 [#981]: https://github.com/lettre/lettre/pull/981
 <a name="v0.11.7"></a>
 ### v0.11.7 (2024-04-23)
 #### Misc
 * Bump `hostname` to v0.4 ([#956])
 * Fix `tracing` message consistency ([#960])
 * Bump minimum required `rustls` to v0.23.5 ([#958])
 * Dropped use of `ref` syntax in the entire project ([#959])
 [#956]: https://github.com/lettre/lettre/pull/956
 [#958]: https://github.com/lettre/lettre/pull/958
 [#959]: https://github.com/lettre/lettre/pull/959
 [#960]: https://github.com/lettre/lettre/pull/960
 <a name="v0.11.6"></a>
 ### v0.11.6 (2024-03-28)
 #### Bug fixes
 * Upgraded `email-encoding` to v0.3 - fixing multiple encoding bugs in the process ([#952])
 #### Misc
 * Updated copyright year in license ([#954])
 [#952]: https://github.com/lettre/lettre/pull/952
 [#954]: https://github.com/lettre/lettre/pull/954
 <a name="v0.11.5"></a>
 ### v0.11.5 (2024-03-25)
 #### Features
 * Support SMTP SASL draft login challenge ([#911])
 * Add conversion from SMTP response code to integer ([#941])
 #### Misc
 * Upgrade `rustls` to v0.23 ([#950])
 * Bump `base64` to v0.22 ([#945])
 * Fix typos in documentation ([#943], [#944])
 * Add `Cargo.lock` ([#942])
 [#911]: https://github.com/lettre/lettre/pull/911
 [#941]: https://github.com/lettre/lettre/pull/941
 [#942]: https://github.com/lettre/lettre/pull/942
 [#943]: https://github.com/lettre/lettre/pull/943
 [#944]: https://github.com/lettre/lettre/pull/944
 [#945]: https://github.com/lettre/lettre/pull/945
 [#950]: https://github.com/lettre/lettre/pull/950
 <a name="v0.11.4"></a>
 ### v0.11.4 (2024-01-28)
@@ -570,6 +414,6 @@ Several breaking changes were made between 0.9 and 0.10, but changes should be s
 *  multipart support
 *  add non-consuming methods for Email builders
-* `add_header` does not return the builder anymore,
+* `add_header` does not return the builder anymore, 
  for consistency with other methods. Use the `header`
  method instead
--- a/Cargo.lock
+++ b/Cargo.lock
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "lettre"
 # remember to update html_root_url and README.md (Cargo.toml example and deps.rs badge)
-version = "0.11.12"
+version = "0.11.4"
 description = "Email client"
 readme = "README.md"
 homepage = "https://lettre.rs"
@@ -11,7 +11,7 @@ authors = ["Alexis Mousset <contact@amousset.me>", "Paolo Barbolini <paolo@paolo
 categories = ["email", "network-programming"]
 keywords = ["email", "smtp", "mailer", "message", "sendmail"]
 edition = "2021"
-rust-version = "1.71"
+rust-version = "1.70"
 [badges]
 is-it-maintained-issue-resolution = { repository = "lettre/lettre" }
@@ -20,7 +20,7 @@ maintenance = { status = "actively-developed" }
 [dependencies]
 chumsky = "0.9"
-idna = "1"
+idna = "0.5"
 tracing = { version = "0.1.16", default-features = false, features = ["std"], optional = true } # feature
 # builder
@@ -29,7 +29,7 @@ mime = { version = "0.3.4", optional = true }
 fastrand = { version = "2.0", optional = true }
 quoted_printable = { version = "0.5", optional = true }
 base64 = { version = "0.22", optional = true }
-email-encoding = { version = "0.3", optional = true }
+email-encoding = { version = "0.2", optional = true }
 # file transport
 uuid = { version = "1", features = ["v4"], optional = true }
@@ -38,17 +38,16 @@ serde_json = { version = "1", optional = true }
 # smtp-transport
 nom = { version = "7", optional = true }
-hostname = { version = "0.4", optional = true } # feature
+hostname = { version = "0.3", optional = true } # feature
 socket2 = { version = "0.5.1", optional = true }
 url = { version = "2.4", optional = true }
 percent-encoding = { version = "2.3", optional = true }
 ## tls
-native-tls = { version = "0.2.9", optional = true } # feature
+native-tls = { version = "0.2.5", optional = true } # feature
-rustls = { version = "0.23.5", default-features = false, features = ["ring", "logging", "std", "tls12"], optional = true }
+rustls = { version = "0.22.1", optional = true }
 rustls-pemfile = { version = "2", optional = true }
-rustls-native-certs = { version = "0.8", optional = true }
+rustls-native-certs = { version = "0.7", optional = true }
 rustls-pki-types = { version = "1.7", optional = true }
 webpki-roots = { version = "0.26", optional = true }
 boring = { version = "4", optional = true }
@@ -59,12 +58,13 @@ async-trait = { version = "0.1", optional = true }
 ## async-std
 async-std = { version = "1.8", optional = true }
-futures-rustls = { version = "0.26", default-features = false, features = ["logging", "tls12", "ring"], optional = true }
+#async-native-tls = { version = "0.3.3", optional = true }
 futures-rustls = { version = "0.25", optional = true }
 ## tokio
 tokio1_crate = { package = "tokio", version = "1", optional = true }
 tokio1_native_tls_crate = { package = "tokio-native-tls", version = "0.3", optional = true }
-tokio1_rustls = { package = "tokio-rustls", version = "0.26", default-features = false, features = ["logging", "tls12", "ring"], optional = true }
+tokio1_rustls = { package = "tokio-rustls", version = "0.25", optional = true }
 tokio1_boring = { package = "tokio-boring", version = "4", optional = true }
 ## dkim
@@ -108,12 +108,13 @@ smtp-transport = ["dep:base64", "dep:nom", "dep:socket2", "dep:url", "dep:percen
 pool = ["dep:futures-util"]
-rustls-tls = ["dep:webpki-roots", "dep:rustls", "dep:rustls-pemfile", "dep:rustls-pki-types"]
+rustls-tls = ["dep:webpki-roots", "dep:rustls", "dep:rustls-pemfile"]
 boring-tls = ["dep:boring"]
 # async
 async-std1 = ["dep:async-std", "dep:async-trait", "dep:futures-io", "dep:futures-util"]
 #async-std1-native-tls = ["async-std1", "native-tls", "dep:async-native-tls"]
 async-std1-rustls-tls = ["async-std1", "rustls-tls", "dep:futures-rustls"]
 tokio1 = ["dep:tokio1_crate", "dep:async-trait", "dep:futures-io", "dep:futures-util"]
 tokio1-native-tls = ["tokio1", "native-tls", "dep:tokio1_native_tls_crate"]
@@ -122,9 +123,6 @@ tokio1-boring-tls = ["tokio1", "boring-tls", "dep:tokio1_boring"]
 dkim = ["dep:base64", "dep:sha2", "dep:rsa", "dep:ed25519-dalek"]
 [lints.rust]
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(lettre_ignore_tls_mismatch)'] }
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs", "--cfg", "lettre_ignore_tls_mismatch"]
--- a/4
+++ b/4
@@ -1,5 +1,5 @@
-Copyright (c) 2014-2024 Alexis Mousset <contact@amousset.me>
+Copyright (c) 2014-2022 Alexis Mousset <contact@amousset.me>
-Copyright (c) 2019-2024 Paolo Barbolini <paolo@paolo565.org>
+Copyright (c) 2019-2022 Paolo Barbolini <paolo@paolo565.org>
 Copyright (c) 2018 K. <kayo@illumium.org>
 Permission is hereby granted, free of charge, to any
--- a/README.md
+++ b/README.md
@@ -28,8 +28,8 @@
 </div>
 <div align="center">
-  <a href="https://deps.rs/crate/lettre/0.11.12">
+  <a href="https://deps.rs/crate/lettre/0.11.4">
-    <img src="https://deps.rs/crate/lettre/0.11.12/status.svg"
+    <img src="https://deps.rs/crate/lettre/0.11.4/status.svg"
      alt="dependency status" />
  </a>
 </div>
@@ -53,12 +53,12 @@ Lettre does not provide (for now):
 ## Supported Rust Versions
 Lettre supports all Rust versions released in the last 6 months. At the time of writing
-the minimum supported Rust version is 1.71, but this could change at any time either from
+the minimum supported Rust version is 1.70, but this could change at any time either from
 one of our dependencies bumping their MSRV or by a new patch release of lettre.
 ## Example
-This library requires Rust 1.71 or newer.
+This library requires Rust 1.70 or newer.
 To use this library, add the following to your `Cargo.toml`:
 ```toml
@@ -71,29 +71,27 @@ use lettre::message::header::ContentType;
 use lettre::transport::smtp::authentication::Credentials;
 use lettre::{Message, SmtpTransport, Transport};
-fn main() {
+let email = Message::builder()
-    let email = Message::builder()
+    .from("NoBody <nobody@domain.tld>".parse().unwrap())
-        .from("NoBody <nobody@domain.tld>".parse().unwrap())
+    .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
-        .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
+    .to("Hei <hei@domain.tld>".parse().unwrap())
-        .to("Hei <hei@domain.tld>".parse().unwrap())
+    .subject("Happy new year")
-        .subject("Happy new year")
+    .header(ContentType::TEXT_PLAIN)
-        .header(ContentType::TEXT_PLAIN)
+    .body(String::from("Be happy!"))
-        .body(String::from("Be happy!"))
+    .unwrap();
        .unwrap();
-    let creds = Credentials::new("smtp_username".to_owned(), "smtp_password".to_owned());
+let creds = Credentials::new("smtp_username".to_owned(), "smtp_password".to_owned());
-    // Open a remote connection to gmail
+// Open a remote connection to gmail
-    let mailer = SmtpTransport::relay("smtp.gmail.com")
+let mailer = SmtpTransport::relay("smtp.gmail.com")
-        .unwrap()
+    .unwrap()
-        .credentials(creds)
+    .credentials(creds)
-        .build();
+    .build();
-    // Send the email
+// Send the email
-    match mailer.send(&email) {
+match mailer.send(&email) {
-        Ok(_) => println!("Email sent successfully!"),
+    Ok(_) => println!("Email sent successfully!"),
-        Err(e) => panic!("Could not send email: {e:?}"),
+    Err(e) => panic!("Could not send email: {e:?}"),
    }
 }
 ```
@@ -107,7 +105,7 @@ cargo run --example autoconfigure SMTP_HOST
 ## Testing
-The `lettre` tests require an open mail server listening locally on port 2525 and the `sendmail` command. If you have python installed
+The `lettre` tests require an open mail server listening locally on port 2525 and the `sendmail` command. If you have python installed 
 such a server can be launched with `python -m smtpd -n -c DebuggingServer 127.0.0.1:2525`
 Alternatively only unit tests can be run by doing `cargo test --lib`.
--- a/benches/transport_smtp.rs
+++ b/benches/transport_smtp.rs
@@ -1,5 +1,5 @@
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
-use lettre::{message::header::ContentType, Message, SmtpTransport, Transport};
+use lettre::{Message, SmtpTransport, Transport};
 fn bench_simple_send(c: &mut Criterion) {
    let sender = SmtpTransport::builder_dangerous("127.0.0.1")
@@ -13,7 +13,6 @@ fn bench_simple_send(c: &mut Criterion) {
                .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
                .to("Hei <hei@domain.tld>".parse().unwrap())
                .subject("Happy new year")
                .header(ContentType::TEXT_PLAIN)
                .body(String::from("Be happy!"))
                .unwrap();
            let result = black_box(sender.send(&email));
@@ -33,7 +32,6 @@ fn bench_reuse_send(c: &mut Criterion) {
                .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
                .to("Hei <hei@domain.tld>".parse().unwrap())
                .subject("Happy new year")
                .header(ContentType::TEXT_PLAIN)
                .body(String::from("Be happy!"))
                .unwrap();
            let result = black_box(sender.send(&email));
--- a/examples/autoconfigure.rs
+++ b/examples/autoconfigure.rs
@@ -41,7 +41,7 @@ fn main() {
    // Plaintext connection which MUST then successfully upgrade to TLS via STARTTLS
    {
-        tracing::info!("Trying to establish a plaintext connection to {} and then upgrading it via the SMTP STARTTLS extension", smtp_host);
+        tracing::info!("Trying to establish a plaintext connection to {} and then updating it via the SMTP STARTTLS extension", smtp_host);
        let transport = SmtpTransport::starttls_relay(&smtp_host)
            .expect("build SmtpTransport::starttls_relay")
--- a/src/address/envelope.rs
+++ b/src/address/envelope.rs
@@ -14,71 +14,11 @@ pub struct Envelope {
    /// The envelope recipient's addresses
    ///
    /// This can not be empty.
    #[cfg_attr(
        feature = "serde",
        serde(deserialize_with = "serde_forward_path::deserialize")
    )]
    forward_path: Vec<Address>,
    /// The envelope sender address
    reverse_path: Option<Address>,
 }
 /// just like the default implementation to deserialize `Vec<Address>` but it
 /// forbids **de**serializing empty lists
 #[cfg(feature = "serde")]
 mod serde_forward_path {
    use super::Address;
    /// dummy type required for serde
    /// see example: <https://serde.rs/deserialize-map.html>
    struct CustomVisitor;
    impl<'de> serde::de::Visitor<'de> for CustomVisitor {
        type Value = Vec<Address>;
        fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
            formatter.write_str("a non-empty list of recipient addresses")
        }
        fn visit_seq<S>(self, mut access: S) -> Result<Self::Value, S::Error>
        where
            S: serde::de::SeqAccess<'de>,
        {
            let mut seq: Vec<Address> = Vec::with_capacity(access.size_hint().unwrap_or(0));
            while let Some(key) = access.next_element()? {
                seq.push(key);
            }
            if seq.is_empty() {
                Err(serde::de::Error::invalid_length(seq.len(), &self))
            } else {
                Ok(seq)
            }
        }
    }
    pub fn deserialize<'de, D>(deserializer: D) -> Result<Vec<Address>, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
        deserializer.deserialize_seq(CustomVisitor {})
    }
    #[cfg(test)]
    mod tests {
        #[test]
        fn deserializing_empty_recipient_list_returns_error() {
            assert!(
                serde_json::from_str::<crate::address::Envelope>(r#"{"forward_path": []}"#)
                    .is_err()
            );
        }
        #[test]
        fn deserializing_non_empty_recipient_list_is_ok() {
            serde_json::from_str::<crate::address::Envelope>(
                r#"{ "forward_path": [ {"user":"foo", "domain":"example.com"} ] }"#,
            )
            .unwrap();
        }
    }
 }
 impl Envelope {
    /// Creates a new envelope, which may fail if `to` is empty.
    ///
--- a/src/address/serde.rs
+++ b/src/address/serde.rs
@@ -36,7 +36,7 @@ impl<'de> Deserialize<'de> for Address {
            {
                struct FieldVisitor;
-                impl Visitor<'_> for FieldVisitor {
+                impl<'de> Visitor<'de> for FieldVisitor {
                    type Value = Field;
                    fn expecting(&self, formatter: &mut Formatter<'_>) -> FmtResult {
--- a/src/executor.rs
+++ b/src/executor.rs
@@ -151,11 +151,11 @@ impl Executor for Tokio1Executor {
        match tls {
            Tls::Opportunistic(tls_parameters) => {
                if conn.can_starttls() {
-                    conn.starttls(tls_parameters.clone(), hello_name).await?;
+                    conn = conn.starttls(tls_parameters.clone(), hello_name).await?;
                }
            }
            Tls::Required(tls_parameters) => {
-                conn.starttls(tls_parameters.clone(), hello_name).await?;
+                conn = conn.starttls(tls_parameters.clone(), hello_name).await?;
            }
            _ => (),
        }
@@ -230,7 +230,7 @@ impl Executor for AsyncStd1Executor {
    ) -> Result<AsyncSmtpConnection, Error> {
        #[allow(clippy::match_single_binding)]
        let tls_parameters = match tls {
-            #[cfg(feature = "async-std1-rustls-tls")]
+            #[cfg(any(feature = "async-std1-native-tls", feature = "async-std1-rustls-tls"))]
            Tls::Wrapper(tls_parameters) => Some(tls_parameters.clone()),
            _ => None,
        };
@@ -243,15 +243,15 @@ impl Executor for AsyncStd1Executor {
        )
        .await?;
-        #[cfg(feature = "async-std1-rustls-tls")]
+        #[cfg(any(feature = "async-std1-native-tls", feature = "async-std1-rustls-tls"))]
        match tls {
            Tls::Opportunistic(tls_parameters) => {
                if conn.can_starttls() {
-                    conn.starttls(tls_parameters.clone(), hello_name).await?;
+                    conn = conn.starttls(tls_parameters.clone(), hello_name).await?;
                }
            }
            Tls::Required(tls_parameters) => {
-                conn.starttls(tls_parameters.clone(), hello_name).await?;
+                conn = conn.starttls(tls_parameters.clone(), hello_name).await?;
            }
            _ => (),
        }
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,7 +6,7 @@
 //! * Secure defaults
 //! * Async support
 //!
-//! Lettre requires Rust 1.71 or newer.
+//! Lettre requires Rust 1.70 or newer.
 //!
 //! ## Features
 //!
@@ -34,25 +34,13 @@
 //!
 //! _Secure SMTP connections using TLS from the `native-tls` crate_
 //!
-//! Uses schannel on Windows, Security-Framework on macOS, and OpenSSL
+//! Uses schannel on Windows, Security-Framework on macOS, and OpenSSL on Linux.
 //! on all other platforms.
 //!
 //! * **native-tls** 📫: TLS support for the synchronous version of the API
 //! * **tokio1-native-tls**: TLS support for the `tokio1` async version of the API
 //!
 //! NOTE: native-tls isn't supported with `async-std`
 //!
 //! ##### Building lettre with OpenSSL
 //!
 //! When building lettre with native-tls on a system that makes
 //! use of OpenSSL, the following packages will need to be installed
 //! in order for the build and the compiled program to run properly.
 //!
 //! | Distro       | Build-time packages        | Runtime packages             |
 //! | ------------ | -------------------------- | ---------------------------- |
 //! | Debian       | `pkg-config`, `libssl-dev` | `libssl3`, `ca-certificates` |
 //! | Alpine Linux | `pkgconf`, `openssl-dev`   | `libssl3`, `ca-certificates` |
 //!
 //! #### SMTP over TLS via the boring crate (Boring TLS)
 //!
 //! _Secure SMTP connections using TLS from the `boring-tls` crate_
@@ -121,7 +109,7 @@
 //! [mime 0.3]: https://docs.rs/mime/0.3
 //! [DKIM]: https://datatracker.ietf.org/doc/html/rfc6376
-#![doc(html_root_url = "https://docs.rs/crate/lettre/0.11.12")]
+#![doc(html_root_url = "https://docs.rs/crate/lettre/0.11.4")]
 #![doc(html_favicon_url = "https://lettre.rs/favicon.ico")]
 #![doc(html_logo_url = "https://avatars0.githubusercontent.com/u/15113230?v=4")]
 #![forbid(unsafe_code)]
@@ -149,14 +137,7 @@
    clippy::wildcard_imports,
    clippy::str_to_string,
    clippy::empty_structs_with_brackets,
-    clippy::zero_sized_map_values,
+    clippy::zero_sized_map_values
    clippy::manual_let_else,
    clippy::semicolon_if_nothing_returned,
    clippy::unnecessary_wraps,
    clippy::doc_markdown,
    clippy::explicit_iter_loop,
    clippy::redundant_closure_for_method_calls,
    // Rust 1.86: clippy::unnecessary_semicolon,
 )]
 #![cfg_attr(docsrs, feature(doc_cfg))]
@@ -193,7 +174,21 @@ mod compiletime_checks {
    If you'd like to use `boring-tls` make sure that the `rustls-tls` feature hasn't been enabled by mistake.
    Make sure to apply the same to any of your crate dependencies that use the `lettre` crate.");
-    #[cfg(all(feature = "async-std1", feature = "native-tls",))]
+    /*
    #[cfg(all(
        feature = "async-std1",
        feature = "native-tls",
        not(feature = "async-std1-native-tls")
    ))]
    compile_error!("Lettre is being built with the `async-std1` and the `native-tls` features, but the `async-std1-native-tls` feature hasn't been turned on.
    If you'd like to use rustls make sure that the `native-tls` hasn't been enabled by mistake (you may need to import lettre without default features)
    If you're building a library which depends on lettre import it without default features and enable just the features you need.");
    */
    #[cfg(all(
        feature = "async-std1",
        feature = "native-tls",
        not(feature = "async-std1-native-tls")
    ))]
    compile_error!("Lettre is being built with the `async-std1` and the `native-tls` features, but the async-std integration doesn't support native-tls yet.
 If you'd like to work on the issue please take a look at https://github.com/lettre/lettre/issues/576.
 If you were trying to opt into `rustls-tls` and did not activate `native-tls`, disable the default-features of lettre in `Cargo.toml` and manually add the required features.
--- a/src/message/dkim.rs
+++ b/src/message/dkim.rs
@@ -69,7 +69,7 @@ impl Display for DkimSigningAlgorithm {
    }
 }
-/// Describe [`DkimSigningKey`] key error
+/// Describe DkimSigning key error
 #[derive(Debug)]
 pub struct DkimSigningKeyError(InnerDkimSigningKeyError);
@@ -100,7 +100,7 @@ impl StdError for DkimSigningKeyError {
    }
 }
-/// Describe a signing key to be carried by [`DkimConfig`] struct
+/// Describe a signing key to be carried by DkimConfig struct
 #[derive(Debug)]
 pub struct DkimSigningKey(InnerDkimSigningKey);
@@ -183,7 +183,7 @@ impl DkimConfig {
        }
    }
-    /// Create a [`DkimConfig`]
+    /// Create a DkimConfig
    pub fn new(
        selector: String,
        domain: String,
@@ -283,19 +283,19 @@ fn dkim_canonicalize_headers_relaxed(headers: &str) -> String {
            // End of header.
            [b'\r', b'\n', ..] => {
                *out += "\r\n";
-                name(&h[2..], out);
+                name(&h[2..], out)
            }
            // Sequential whitespace.
            [b' ' | b'\t', b' ' | b'\t' | b'\r', ..] => value(&h[1..], out),
            // All whitespace becomes spaces.
            [b'\t', ..] => {
                out.push(' ');
-                value(&h[1..], out);
+                value(&h[1..], out)
            }
            [_, ..] => {
                let mut chars = h.chars();
                out.push(chars.next().unwrap());
-                value(chars.as_str(), out);
+                value(chars.as_str(), out)
            }
            [] => {}
        }
@@ -317,7 +317,7 @@ fn dkim_canonicalize_header_tag(
    }
 }
-/// Canonicalize signed headers passed as `headers_list` among `mail_headers` using canonicalization
+/// Canonicalize signed headers passed as headers_list among mail_headers using canonicalization
 fn dkim_canonicalize_headers<'a>(
    headers_list: impl IntoIterator<Item = &'a str>,
    mail_headers: &Headers,
@@ -344,9 +344,10 @@ fn dkim_canonicalize_headers<'a>(
 }
 /// Sign with Dkim a message by adding Dkim-Signature header created with configuration expressed by
-/// `dkim_config`
+/// dkim_config
 pub fn dkim_sign(message: &mut Message, dkim_config: &DkimConfig) {
-    dkim_sign_fixed_time(message, dkim_config, SystemTime::now());
+    dkim_sign_fixed_time(message, dkim_config, SystemTime::now())
 }
 fn dkim_sign_fixed_time(message: &mut Message, dkim_config: &DkimConfig, timestamp: SystemTime) {
@@ -377,7 +378,7 @@ fn dkim_sign_fixed_time(message: &mut Message, dkim_config: &DkimConfig, timesta
    }
    let dkim_header = dkim_header_format(dkim_config, timestamp, &signed_headers_list, &bh, "");
    let signed_headers = dkim_canonicalize_headers(
-        dkim_config.headers.iter().map(AsRef::as_ref),
+        dkim_config.headers.iter().map(|h| h.as_ref()),
        headers,
        dkim_config.canonicalization.header,
    );
@@ -487,14 +488,14 @@ cJ5Ku0OTwRtSMaseRPX+T4EfG1Caa/eunPPN4rh+CSup2BVVarOT
    fn test_headers_simple_canonicalize() {
        let message = test_message();
        dbg!(message.headers.to_string());
-        assert_eq!(dkim_canonicalize_headers(["From", "Test"], &message.headers, DkimCanonicalizationType::Simple), "From: =?utf-8?b?VGVzdCBPJ0xlYXJ5?= <test+ezrz@example.net>\r\nTest: test  test very very long with spaces and extra spaces   \twill be\r\n folded to several lines \r\n");
+        assert_eq!(dkim_canonicalize_headers(["From", "Test"], &message.headers, DkimCanonicalizationType::Simple), "From: =?utf-8?b?VGVzdCBPJ0xlYXJ5?= <test+ezrz@example.net>\r\nTest: test  test very very long with spaces and extra spaces   \twill be\r\n folded to several lines \r\n")
    }
    #[test]
    fn test_headers_relaxed_canonicalize() {
        let message = test_message();
        dbg!(message.headers.to_string());
-        assert_eq!(dkim_canonicalize_headers(["From", "Test"], &message.headers, DkimCanonicalizationType::Relaxed),"from:=?utf-8?b?VGVzdCBPJ0xlYXJ5?= <test+ezrz@example.net>\r\ntest:test test very very long with spaces and extra spaces will be folded to several lines\r\n");
+        assert_eq!(dkim_canonicalize_headers(["From", "Test"], &message.headers, DkimCanonicalizationType::Relaxed),"from:=?utf-8?b?VGVzdCBPJ0xlYXJ5?= <test+ezrz@example.net>\r\ntest:test test very very long with spaces and extra spaces will be folded to several lines\r\n")
    }
    #[test]
--- a/src/message/header/content_disposition.rs
+++ b/src/message/header/content_disposition.rs
@@ -1,6 +1,6 @@
 use std::fmt::Write;
-use email_encoding::headers::writer::EmailWriter;
+use email_encoding::headers::EmailWriter;
 use super::{Header, HeaderName, HeaderValue};
 use crate::BoxError;
@@ -38,10 +38,10 @@ impl ContentDisposition {
        let mut encoded_value = String::new();
        let line_len = "Content-Disposition: ".len();
        {
-            let mut w = EmailWriter::new(&mut encoded_value, line_len, 0, false);
+            let mut w = EmailWriter::new(&mut encoded_value, line_len, 0, false, false);
            w.write_str(kind).expect("writing `kind` returned an error");
            w.write_char(';').expect("writing `;` returned an error");
-            w.space();
+            w.optional_breakpoint();
            email_encoding::headers::rfc2231::encode("filename", file_name, &mut w)
                .expect("some Write implementation returned an error");
--- a/src/message/header/content_type.rs
+++ b/src/message/header/content_type.rs
@@ -119,7 +119,7 @@ mod serde {
        {
            struct ContentTypeVisitor;
-            impl Visitor<'_> for ContentTypeVisitor {
+            impl<'de> Visitor<'de> for ContentTypeVisitor {
                type Value = ContentType;
                // The error message which states what the Visitor expects to
--- a/src/message/header/mailbox.rs
+++ b/src/message/header/mailbox.rs
@@ -1,4 +1,4 @@
-use email_encoding::headers::writer::EmailWriter;
+use email_encoding::headers::EmailWriter;
 use super::{Header, HeaderName, HeaderValue};
 use crate::{
@@ -31,7 +31,7 @@ macro_rules! mailbox_header {
                let mut encoded_value = String::new();
                let line_len = $header_name.len() + ": ".len();
                {
-                    let mut w = EmailWriter::new(&mut encoded_value, line_len, 0, false);
+                    let mut w = EmailWriter::new(&mut encoded_value, line_len, 0, false, false);
                    self.0.encode(&mut w).expect("writing `Mailbox` returned an error");
                }
@@ -81,7 +81,7 @@ macro_rules! mailboxes_header {
                let mut encoded_value = String::new();
                let line_len = $header_name.len() + ": ".len();
                {
-                    let mut w = EmailWriter::new(&mut encoded_value, line_len, 0, false);
+                    let mut w = EmailWriter::new(&mut encoded_value, line_len, 0, false, false);
                    self.0.encode(&mut w).expect("writing `Mailboxes` returned an error");
                }
@@ -110,7 +110,7 @@ mailbox_header! {
    `Sender` header
-    This header contains [`Mailbox`] associated with sender.
+    This header contains [`Mailbox`][self::Mailbox] associated with sender.
    ```no_test
    header::Sender("Mr. Sender <sender@example.com>".parse().unwrap())
@@ -124,7 +124,7 @@ mailboxes_header! {
    `From` header
-    This header contains [`Mailboxes`].
+    This header contains [`Mailboxes`][self::Mailboxes].
     */
    (From, "From")
@@ -135,7 +135,7 @@ mailboxes_header! {
    `Reply-To` header
-    This header contains [`Mailboxes`].
+    This header contains [`Mailboxes`][self::Mailboxes].
     */
    (ReplyTo, "Reply-To")
@@ -146,7 +146,7 @@ mailboxes_header! {
    `To` header
-    This header contains [`Mailboxes`].
+    This header contains [`Mailboxes`][self::Mailboxes].
     */
    (To, "To")
@@ -157,7 +157,7 @@ mailboxes_header! {
    `Cc` header
-    This header contains [`Mailboxes`].
+    This header contains [`Mailboxes`][self::Mailboxes].
     */
    (Cc, "Cc")
@@ -168,7 +168,7 @@ mailboxes_header! {
    `Bcc` header
-    This header contains [`Mailboxes`].
+    This header contains [`Mailboxes`][self::Mailboxes].
     */
    (Bcc, "Bcc")
--- a/src/message/header/mod.rs
+++ b/src/message/header/mod.rs
@@ -7,7 +7,7 @@ use std::{
    ops::Deref,
 };
-use email_encoding::headers::writer::EmailWriter;
+use email_encoding::headers::EmailWriter;
 pub use self::{
    content::*,
@@ -124,18 +124,22 @@ impl Headers {
    }
    pub(crate) fn find_header(&self, name: &str) -> Option<&HeaderValue> {
-        self.headers.iter().find(|value| name == value.name)
+        self.headers
            .iter()
            .find(|value| name.eq_ignore_ascii_case(&value.name))
    }
    fn find_header_mut(&mut self, name: &str) -> Option<&mut HeaderValue> {
-        self.headers.iter_mut().find(|value| name == value.name)
+        self.headers
            .iter_mut()
            .find(|value| name.eq_ignore_ascii_case(&value.name))
    }
    fn find_header_index(&self, name: &str) -> Option<usize> {
        self.headers
            .iter()
            .enumerate()
-            .find(|(_i, value)| name == value.name)
+            .find(|(_i, value)| name.eq_ignore_ascii_case(&value.name))
            .map(|(i, _)| i)
    }
 }
@@ -157,9 +161,18 @@ impl Display for Headers {
 /// A possible error when converting a `HeaderName` from another type.
 // comes from `http` crate
 #[allow(missing_copy_implementations)]
-#[derive(Debug, Clone)]
+#[derive(Clone)]
-#[non_exhaustive]
+pub struct InvalidHeaderName {
-pub struct InvalidHeaderName;
+    _priv: (),
 }
 impl fmt::Debug for InvalidHeaderName {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("InvalidHeaderName")
            // skip _priv noise
            .finish()
    }
 }
 impl fmt::Display for InvalidHeaderName {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -176,11 +189,14 @@ pub struct HeaderName(Cow<'static, str>);
 impl HeaderName {
    /// Creates a new header name
    pub fn new_from_ascii(ascii: String) -> Result<Self, InvalidHeaderName> {
-        if !ascii.is_empty() && ascii.len() <= 76 && ascii.is_ascii() && !ascii.contains([':', ' '])
+        if !ascii.is_empty()
            && ascii.len() <= 76
            && ascii.is_ascii()
            && !ascii.contains(|c| c == ':' || c == ' ')
        {
            Ok(Self(Cow::Owned(ascii)))
        } else {
-            Err(InvalidHeaderName)
+            Err(InvalidHeaderName { _priv: () })
        }
    }
@@ -241,19 +257,23 @@ impl AsRef<str> for HeaderName {
 impl PartialEq<HeaderName> for HeaderName {
    fn eq(&self, other: &HeaderName) -> bool {
-        self.eq_ignore_ascii_case(other)
+        let s1: &str = self.as_ref();
        let s2: &str = other.as_ref();
        s1 == s2
    }
 }
 impl PartialEq<&str> for HeaderName {
    fn eq(&self, other: &&str) -> bool {
-        self.eq_ignore_ascii_case(other)
+        let s: &str = self.as_ref();
        s == *other
    }
 }
 impl PartialEq<HeaderName> for &str {
    fn eq(&self, other: &HeaderName) -> bool {
-        self.eq_ignore_ascii_case(other)
+        let s: &str = other.as_ref();
        *self == s
    }
 }
@@ -328,7 +348,7 @@ impl<'a> HeaderValueEncoder<'a> {
    fn new(name: &str, writer: &'a mut dyn Write) -> Self {
        let line_len = name.len() + ": ".len();
-        let writer = EmailWriter::new(writer, line_len, 0, false);
+        let writer = EmailWriter::new(writer, line_len, 0, false, false);
        Self {
            writer,
@@ -415,7 +435,7 @@ mod tests {
    #[test]
    fn empty_headername() {
-        assert!(HeaderName::new_from_ascii("".to_owned()).is_err());
+        assert!(HeaderName::new_from_ascii(String::from("")).is_err());
    }
    #[test]
@@ -447,60 +467,6 @@ mod tests {
        let _ = HeaderName::new_from_ascii_str("");
    }
    #[test]
    fn headername_headername_eq() {
        assert_eq!(
            HeaderName::new_from_ascii_str("From"),
            HeaderName::new_from_ascii_str("From")
        );
    }
    #[test]
    fn headername_str_eq() {
        assert_eq!(HeaderName::new_from_ascii_str("From"), "From");
    }
    #[test]
    fn str_headername_eq() {
        assert_eq!("From", HeaderName::new_from_ascii_str("From"));
    }
    #[test]
    fn headername_headername_eq_case_insensitive() {
        assert_eq!(
            HeaderName::new_from_ascii_str("From"),
            HeaderName::new_from_ascii_str("from")
        );
    }
    #[test]
    fn headername_str_eq_case_insensitive() {
        assert_eq!(HeaderName::new_from_ascii_str("From"), "from");
    }
    #[test]
    fn str_headername_eq_case_insensitive() {
        assert_eq!("from", HeaderName::new_from_ascii_str("From"));
    }
    #[test]
    fn headername_headername_ne() {
        assert_ne!(
            HeaderName::new_from_ascii_str("From"),
            HeaderName::new_from_ascii_str("To")
        );
    }
    #[test]
    fn headername_str_ne() {
        assert_ne!(HeaderName::new_from_ascii_str("From"), "To");
    }
    #[test]
    fn str_headername_ne() {
        assert_ne!("From", HeaderName::new_from_ascii_str("To"));
    }
    // names taken randomly from https://it.wikipedia.org/wiki/Pinco_Pallino
    #[test]
@@ -646,14 +612,17 @@ mod tests {
            "🌍 <world@example.com>, 🦆 Everywhere <ducks@example.com>, Иванов Иван Иванович <ivanov@example.com>, Jānis Bērziņš <janis@example.com>, Seán Ó Rudaí <sean@example.com>".to_owned(),
        ));
        // TODO: fix the fact that the encoder doesn't know that
        // the space between the name and the address should be
        // removed when wrapping.
        assert_eq!(
            headers.to_string(),
            concat!(
                "To: =?utf-8?b?8J+MjQ==?= <world@example.com>, =?utf-8?b?8J+mhg==?=\r\n",
                " Everywhere <ducks@example.com>, =?utf-8?b?0JjQstCw0L3QvtCyINCY0LLQsNC9?=\r\n",
                " =?utf-8?b?INCY0LLQsNC90L7QstC40Yc=?= <ivanov@example.com>,\r\n",
-                " =?utf-8?b?SsSBbmlzIELEk3J6acWGxaE=?= <janis@example.com>, =?utf-8?b?U2U=?=\r\n",
+                "  =?utf-8?b?SsSBbmlzIELEk3J6acWGxaE=?= <janis@example.com>,\r\n",
-                " =?utf-8?b?w6FuIMOTIFJ1ZGHDrQ==?= <sean@example.com>\r\n",
+                "  =?utf-8?b?U2XDoW4gw5MgUnVkYcOt?= <sean@example.com>\r\n",
            )
        );
    }
@@ -718,6 +687,9 @@ mod tests {
            "quoted-printable".to_owned(),
        ));
        // TODO: fix the fact that the encoder doesn't know that
        // the space between the name and the address should be
        // removed when wrapping.
        assert_eq!(
            headers.to_string(),
            concat!(
@@ -727,8 +699,8 @@ mod tests {
                "To: =?utf-8?b?8J+MjQ==?= <world@example.com>, =?utf-8?b?8J+mhg==?=\r\n",
                " Everywhere <ducks@example.com>, =?utf-8?b?0JjQstCw0L3QvtCyINCY0LLQsNC9?=\r\n",
                " =?utf-8?b?INCY0LLQsNC90L7QstC40Yc=?= <ivanov@example.com>,\r\n",
-                " =?utf-8?b?SsSBbmlzIELEk3J6acWGxaE=?= <janis@example.com>, =?utf-8?b?U2U=?=\r\n",
+                "  =?utf-8?b?SsSBbmlzIELEk3J6acWGxaE=?= <janis@example.com>,\r\n",
-                " =?utf-8?b?w6FuIMOTIFJ1ZGHDrQ==?= <sean@example.com>\r\n",
+                "  =?utf-8?b?U2XDoW4gw5MgUnVkYcOt?= <sean@example.com>\r\n",
                "From: Someone <somewhere@example.com>\r\n",
                "Content-Transfer-Encoding: quoted-printable\r\n",
            )
--- a/src/message/mailbox/parsers/rfc2822.rs
+++ b/src/message/mailbox/parsers/rfc2822.rs
@@ -170,9 +170,7 @@ fn phrase() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
 // mailbox         =       name-addr / addr-spec
 pub(crate) fn mailbox() -> impl Parser<char, (Option<String>, (String, String)), Error = Cheap<char>>
 {
-    choice((name_addr(), addr_spec().map(|addr| (None, addr))))
+    choice((name_addr(), addr_spec().map(|addr| (None, addr)))).then_ignore(end())
        .padded()
        .then_ignore(end())
 }
 // name-addr       =       [display-name] angle-addr
--- a/src/message/mailbox/serde.rs
+++ b/src/message/mailbox/serde.rs
@@ -36,7 +36,7 @@ impl<'de> Deserialize<'de> for Mailbox {
            {
                struct FieldVisitor;
-                impl Visitor<'_> for FieldVisitor {
+                impl<'de> Visitor<'de> for FieldVisitor {
                    type Value = Field;
                    fn expecting(&self, formatter: &mut Formatter<'_>) -> FmtResult {
--- a/src/message/mailbox/types.rs
+++ b/src/message/mailbox/types.rs
@@ -6,7 +6,7 @@ use std::{
 };
 use chumsky::prelude::*;
-use email_encoding::headers::writer::EmailWriter;
+use email_encoding::headers::EmailWriter;
 use super::parsers;
 use crate::address::{Address, AddressError};
@@ -72,7 +72,7 @@ impl Mailbox {
    pub(crate) fn encode(&self, w: &mut EmailWriter<'_>) -> FmtResult {
        if let Some(name) = &self.name {
            email_encoding::headers::quoted_string::encode(name, w)?;
-            w.space();
+            w.optional_breakpoint();
            w.write_char('<')?;
        }
@@ -174,7 +174,7 @@ impl Mailboxes {
        self
    }
-    /// Adds a new [`Mailbox`] to the list, in a `Vec::push` style pattern.
+    /// Adds a new [`Mailbox`] to the list, in a Vec::push style pattern.
    ///
    /// # Examples
    ///
@@ -261,7 +261,7 @@ impl Mailboxes {
        for mailbox in self.iter() {
            if !mem::take(&mut first) {
                w.write_char(',')?;
-                w.space();
+                w.optional_breakpoint();
            }
            mailbox.encode(w)?;
@@ -351,7 +351,7 @@ impl FromStr for Mailboxes {
        })?;
        for (name, (user, domain)) in parsed_mailboxes {
-            mailboxes.push(Mailbox::new(name, Address::new(user, domain)?));
+            mailboxes.push(Mailbox::new(name, Address::new(user, domain)?))
        }
        Ok(Mailboxes(mailboxes))
@@ -444,6 +444,8 @@ fn write_quoted_string_char(f: &mut Formatter<'_>, c: char) -> FmtResult {
 #[cfg(test)]
 mod test {
    use std::convert::TryInto;
    use pretty_assertions::assert_eq;
    use super::Mailbox;
@@ -531,7 +533,7 @@ mod test {
        assert_eq!(
            format!(
                "{}",
-                Mailbox::new(Some("".to_owned()), "kayo@example.com".parse().unwrap())
+                Mailbox::new(Some("".into()), "kayo@example.com".parse().unwrap())
            ),
            "kayo@example.com"
        );
@@ -556,14 +558,6 @@ mod test {
        );
    }
    #[test]
    fn parse_address_only_trim() {
        assert_eq!(
            " kayo@example.com ".parse(),
            Ok(Mailbox::new(None, "kayo@example.com".parse().unwrap()))
        );
    }
    #[test]
    fn parse_address_with_name() {
        assert_eq!(
@@ -575,17 +569,6 @@ mod test {
        );
    }
    #[test]
    fn parse_address_with_name_trim() {
        assert_eq!(
            " K. <kayo@example.com> ".parse(),
            Ok(Mailbox::new(
                Some("K.".into()),
                "kayo@example.com".parse().unwrap()
            ))
        );
    }
    #[test]
    fn parse_address_with_empty_name() {
        assert_eq!(
@@ -597,7 +580,7 @@ mod test {
    #[test]
    fn parse_address_with_empty_name_trim() {
        assert_eq!(
-            " <kayo@example.com> ".parse(),
+            " <kayo@example.com>".parse(),
            Ok(Mailbox::new(None, "kayo@example.com".parse().unwrap()))
        );
    }
--- a/src/message/mimebody.rs
+++ b/src/message/mimebody.rs
@@ -420,6 +420,7 @@ mod test {
    use pretty_assertions::assert_eq;
    use super::*;
    use crate::message::header;
    #[test]
    fn single_part_binary() {
--- a/src/message/mod.rs
+++ b/src/message/mod.rs
@@ -345,7 +345,7 @@ impl MessageBuilder {
                let hostname = hostname::get()
                    .map_err(|_| ())
                    .and_then(|s| s.into_string().map_err(|_| ()))
-                    .unwrap_or_else(|()| DEFAULT_MESSAGE_ID_DOMAIN.to_owned());
+                    .unwrap_or_else(|_| DEFAULT_MESSAGE_ID_DOMAIN.to_owned());
                #[cfg(not(feature = "hostname"))]
                let hostname = DEFAULT_MESSAGE_ID_DOMAIN.to_owned();
@@ -457,12 +457,12 @@ impl MessageBuilder {
        self.build(MessageBody::Raw(body.into_vec()))
    }
-    /// Create message using mime body ([`MultiPart`])
+    /// Create message using mime body ([`MultiPart`][self::MultiPart])
    pub fn multipart(self, part: MultiPart) -> Result<Message, EmailError> {
        self.mime_1_0().build(MessageBody::Mime(Part::Multi(part)))
    }
-    /// Create message using mime body ([`SinglePart`])
+    /// Create message using mime body ([`SinglePart`][self::SinglePart])
    pub fn singlepart(self, part: SinglePart) -> Result<Message, EmailError> {
        self.mime_1_0().build(MessageBody::Mime(Part::Single(part)))
    }
@@ -527,7 +527,7 @@ impl Message {
        match &self.body {
            MessageBody::Mime(p) => p.format_body(&mut out),
            MessageBody::Raw(r) => out.extend_from_slice(r),
-        }
+        };
        out.extend_from_slice(b"\r\n");
        out
    }
@@ -537,10 +537,7 @@ impl Message {
    /// Example:
    /// ```rust
    /// use lettre::{
-    ///     message::{
+    ///     message::dkim::{DkimConfig, DkimSigningAlgorithm, DkimSigningKey},
    ///         dkim::{DkimConfig, DkimSigningAlgorithm, DkimSigningKey},
    ///         header::ContentType,
    ///     },
    ///     Message,
    /// };
    ///
@@ -549,7 +546,6 @@ impl Message {
    ///     .reply_to("Bob <bob@example.org>".parse().unwrap())
    ///     .to("Carla <carla@example.net>".parse().unwrap())
    ///     .subject("Hello")
    ///     .header(ContentType::TEXT_PLAIN)
    ///     .body("Hi there, it's a test email, with utf-8 chars ë!\n\n\n".to_owned())
    ///     .unwrap();
    /// let key = "-----BEGIN RSA PRIVATE KEY-----
@@ -605,7 +601,7 @@ impl EmailFormat for Message {
            MessageBody::Mime(p) => p.format(out),
            MessageBody::Raw(r) => {
                out.extend_from_slice(b"\r\n");
-                out.extend_from_slice(r);
+                out.extend_from_slice(r)
            }
        }
    }
@@ -769,7 +765,7 @@ mod test {
                continue;
            }
-            assert_eq!(line.0, line.1);
+            assert_eq!(line.0, line.1)
        }
    }
--- a/src/transport/file/error.rs
+++ b/src/transport/file/error.rs
@@ -68,7 +68,7 @@ impl fmt::Display for Error {
            Kind::Io => f.write_str("response error")?,
            #[cfg(feature = "file-transport-envelope")]
            Kind::Envelope => f.write_str("internal client error")?,
-        }
+        };
        if let Some(e) = &self.inner.source {
            write!(f, ": {e}")?;
--- a/src/transport/file/mod.rs
+++ b/src/transport/file/mod.rs
@@ -11,7 +11,7 @@
 //! # fn main() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{message::header::ContentType, FileTransport, Message, Transport};
+//! use lettre::{FileTransport, Message, Transport};
 //!
 //! // Write to the local temp directory
 //! let sender = FileTransport::new(temp_dir());
@@ -20,10 +20,10 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
-//! sender.send(&email)?;
+//! let result = sender.send(&email);
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //!
@@ -44,7 +44,7 @@
 //! # fn main() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{message::header::ContentType, FileTransport, Message, Transport};
+//! use lettre::{FileTransport, Message, Transport};
 //!
 //! // Write to the local temp directory
 //! let sender = FileTransport::with_envelope(temp_dir());
@@ -53,10 +53,10 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
-//! sender.send(&email)?;
+//! let result = sender.send(&email);
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //!
@@ -73,9 +73,7 @@
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{
+//! use lettre::{AsyncFileTransport, AsyncTransport, Message, Tokio1Executor};
 //!     message::header::ContentType, AsyncFileTransport, AsyncTransport, Message, Tokio1Executor,
 //! };
 //!
 //! // Write to the local temp directory
 //! let sender = AsyncFileTransport::<Tokio1Executor>::new(temp_dir());
@@ -84,10 +82,10 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
-//! sender.send(email).await?;
+//! let result = sender.send(email).await;
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //! ```
@@ -101,10 +99,7 @@
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use std::env::temp_dir;
 //!
-//! use lettre::{
+//! use lettre::{AsyncFileTransport, AsyncStd1Executor, AsyncTransport, Message};
 //!     message::header::ContentType, AsyncFileTransport, AsyncStd1Executor, AsyncTransport,
 //!     Message,
 //! };
 //!
 //! // Write to the local temp directory
 //! let sender = AsyncFileTransport::<AsyncStd1Executor>::new(temp_dir());
@@ -113,10 +108,10 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
-//! sender.send(email).await?;
+//! let result = sender.send(email).await;
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //! ```
@@ -130,7 +125,6 @@
 //! Reply-To: Yuin <yuin@domain.tld>
 //! To: Hei <hei@domain.tld>
 //! Subject: Happy new year
 //! Content-Type: text/plain; charset=utf-8
 //! Date: Tue, 18 Aug 2020 22:50:17 GMT
 //!
 //! Be happy!
--- a/src/transport/mod.rs
+++ b/src/transport/mod.rs
@@ -12,7 +12,7 @@
 //!
 //! * a service from your Cloud or hosting provider
 //! * an email server ([MTA] for Mail Transfer Agent, like Postfix or Exchange), running either
-//!   locally on your servers or accessible over the network
+//! locally on your servers or accessible over the network
 //! * a dedicated external service, like Mailchimp, Mailgun, etc.
 //!
 //! In most cases, the best option is to:
@@ -56,17 +56,13 @@
 //! #
 //! # #[cfg(all(feature = "builder", feature = "smtp-transport"))]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::{
+//! use lettre::{transport::smtp::authentication::Credentials, Message, SmtpTransport, Transport};
 //!     message::header::ContentType, transport::smtp::authentication::Credentials, Message,
 //!     SmtpTransport, Transport,
 //! };
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let creds = Credentials::new("smtp_username".to_owned(), "smtp_password".to_owned());
--- a/src/transport/sendmail/error.rs
+++ b/src/transport/sendmail/error.rs
@@ -65,7 +65,7 @@ impl fmt::Display for Error {
        match self.inner.kind {
            Kind::Response => f.write_str("response error")?,
            Kind::Client => f.write_str("internal client error")?,
-        }
+        };
        if let Some(e) = &self.inner.source {
            write!(f, ": {e}")?;
--- a/src/transport/sendmail/mod.rs
+++ b/src/transport/sendmail/mod.rs
@@ -7,18 +7,18 @@
 //! #
 //! # #[cfg(all(feature = "sendmail-transport", feature = "builder"))]
 //! # fn main() -> Result<(), Box<dyn Error>> {
-//! use lettre::{message::header::ContentType, Message, SendmailTransport, Transport};
+//! use lettre::{Message, SendmailTransport, Transport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let sender = SendmailTransport::new();
-//! sender.send(&email)?;
+//! let result = sender.send(&email);
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //!
@@ -34,8 +34,7 @@
 //! # #[cfg(all(feature = "tokio1", feature = "sendmail-transport", feature = "builder"))]
 //! # async fn run() -> Result<(), Box<dyn Error>> {
 //! use lettre::{
-//!     message::header::ContentType, AsyncSendmailTransport, AsyncTransport, Message,
+//!     AsyncSendmailTransport, AsyncTransport, Message, SendmailTransport, Tokio1Executor,
 //!     SendmailTransport, Tokio1Executor,
 //! };
 //!
 //! let email = Message::builder()
@@ -43,11 +42,11 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let sender = AsyncSendmailTransport::<Tokio1Executor>::new();
-//! sender.send(email).await?;
+//! let result = sender.send(email).await;
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //! ```
@@ -59,17 +58,18 @@
 //! #
 //! # #[cfg(all(feature = "async-std1", feature = "sendmail-transport", feature = "builder"))]
 //! # async fn run() -> Result<(), Box<dyn Error>> {
-//! use lettre::{Message, AsyncTransport, AsyncStd1Executor,message::header::ContentType, AsyncSendmailTransport};
+//! use lettre::{Message, AsyncTransport, AsyncStd1Executor, AsyncSendmailTransport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
-//!     .subject("Happy new year").header(ContentType::TEXT_PLAIN)
+//!     .subject("Happy new year")
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let sender = AsyncSendmailTransport::<AsyncStd1Executor>::new();
-//! sender.send(email).await?;
+//! let result = sender.send(email).await;
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //! ```
@@ -120,7 +120,7 @@ impl SendmailTransport {
    /// Creates a new transport with the `sendmail` command
    ///
    /// Note: This uses the `sendmail` command in the current `PATH`. To use another command,
-    /// use [`SendmailTransport::new_with_command`].
+    /// use [SendmailTransport::new_with_command].
    pub fn new() -> SendmailTransport {
        SendmailTransport {
            command: DEFAULT_SENDMAIL.into(),
@@ -157,7 +157,7 @@ where
    /// Creates a new transport with the `sendmail` command
    ///
    /// Note: This uses the `sendmail` command in the current `PATH`. To use another command,
-    /// use [`AsyncSendmailTransport::new_with_command`].
+    /// use [AsyncSendmailTransport::new_with_command].
    pub fn new() -> Self {
        Self {
            inner: SendmailTransport::new(),
--- a/src/transport/smtp/async_transport.rs
+++ b/src/transport/smtp/async_transport.rs
@@ -12,12 +12,6 @@ use async_trait::async_trait;
 use super::pool::async_impl::Pool;
 #[cfg(feature = "pool")]
 use super::PoolConfig;
 #[cfg(any(
    feature = "tokio1-native-tls",
    feature = "tokio1-rustls-tls",
    feature = "async-std1-rustls-tls"
 ))]
 use super::Tls;
 use super::{
    client::AsyncSmtpConnection, ClientId, Credentials, Error, Mechanism, Response, SmtpInfo,
 };
@@ -30,30 +24,6 @@ use crate::Tokio1Executor;
 use crate::{Envelope, Executor};
 /// Asynchronously sends emails using the SMTP protocol
 ///
 /// `AsyncSmtpTransport` is the primary way for communicating
 /// with SMTP relay servers to send email messages. It holds the
 /// client connect configuration and creates new connections
 /// as necessary.
 ///
 /// # Connection pool
 ///
 /// When the `pool` feature is enabled (default), `AsyncSmtpTransport` maintains a
 /// connection pool to manage SMTP connections. The pool:
 ///
 /// - Establishes a new connection when sending a message.
 /// - Recycles connections internally after a message is sent.
 /// - Reuses connections for subsequent messages, reducing connection setup overhead.
 ///
 /// The connection pool can grow to hold multiple SMTP connections if multiple
 /// emails are sent concurrently, as SMTP does not support multiplexing within a
 /// single connection.
 ///
 /// However, **connection reuse is not possible** if the `SyncSmtpTransport` instance
 /// is dropped after every email send operation. You must reuse the instance
 /// of this struct for the connection pool to be of any use.
 ///
 /// To customize connection pool settings, use [`AsyncSmtpTransportBuilder::pool_config`].
 #[cfg_attr(docsrs, doc(cfg(any(feature = "tokio1", feature = "async-std1"))))]
 pub struct AsyncSmtpTransport<E: Executor> {
    #[cfg(feature = "pool")]
@@ -75,7 +45,7 @@ impl AsyncTransport for AsyncSmtpTransport<Tokio1Executor> {
        let result = conn.send(envelope, email).await?;
        #[cfg(not(feature = "pool"))]
-        conn.abort().await;
+        conn.quit().await?;
        Ok(result)
    }
@@ -112,6 +82,7 @@ where
    #[cfg(any(
        feature = "tokio1-native-tls",
        feature = "tokio1-rustls-tls",
        feature = "async-std1-native-tls",
        feature = "async-std1-rustls-tls"
    ))]
    #[cfg_attr(
@@ -146,6 +117,7 @@ where
    #[cfg(any(
        feature = "tokio1-native-tls",
        feature = "tokio1-rustls-tls",
        feature = "async-std1-native-tls",
        feature = "async-std1-rustls-tls"
    ))]
    #[cfg_attr(
@@ -191,72 +163,54 @@ where
    /// Creates a `AsyncSmtpTransportBuilder` from a connection URL
    ///
-    /// The protocol, credentials, host, port and EHLO name can be provided
+    /// The protocol, credentials, host and port can be provided in a single URL.
-    /// in a single URL. This may be simpler than having to configure SMTP
+    /// Use the scheme `smtp` for an unencrypted relay (optionally in combination with the
-    /// through multiple configuration parameters and then having to pass
+    /// `tls` parameter to allow/require STARTTLS) or `smtps` for SMTP over TLS.
-    /// those options to lettre.
+    /// The path section of the url can be used to set an alternative name for
    /// the HELO / EHLO command.
    /// For example `smtps://username:password@smtp.example.com/client.example.com:465`
    /// will set the HELO / EHLO name `client.example.com`.
    ///
-    /// The URL is created in the following way:
+    /// <table>
-    /// `scheme://user:pass@hostname:port/ehlo-name?tls=TLS`.
+    ///   <thead>
-    ///
+    ///     <tr>
-    /// `user` (Username) and `pass` (Password) are optional in case the
+    ///       <th>scheme</th>
-    /// SMTP relay doesn't require authentication. When `port` is not
+    ///       <th>tls parameter</th>
-    /// configured it is automatically determined based on the `scheme`.
+    ///       <th>example</th>
-    /// `ehlo-name` optionally overwrites the hostname sent for the EHLO
+    ///       <th>remarks</th>
-    /// command. `TLS` controls whether STARTTLS is simply enabled
+    ///     </tr>
-    /// (`opportunistic` - not enough to prevent man-in-the-middle attacks)
+    ///   </thead>
-    /// or `required` (require the server to upgrade the connection to
+    ///   <tbody>
-    /// STARTTLS, otherwise fail on suspicion of main-in-the-middle attempt).
+    ///     <tr>
-    ///
+    ///      <td>smtps</td>
-    /// Use the following table to construct your SMTP url:
+    ///      <td>-</td>
-    ///
+    ///      <td>smtps://smtp.example.com</td>
-    /// | scheme  | `tls` query parameter | example                                            | default port | remarks                                                                                                                               |
+    ///      <td>SMTP over TLS, recommended method</td>
-    /// | ------- | --------------------- | -------------------------------------------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------- |
+    ///     </tr>
-    /// | `smtps` | unset                 | `smtps://user:pass@hostname:port`                  | 465          | SMTP over TLS, recommended method                                                                                                     |
+    ///     <tr>
-    /// | `smtp`  | `required`            | `smtp://user:pass@hostname:port?tls=required`      | 587          | SMTP with STARTTLS required, when SMTP over TLS is not available                                                                      |
+    ///      <td>smtp</td>
-    /// | `smtp`  | `opportunistic`       | `smtp://user:pass@hostname:port?tls=opportunistic` | 587          | SMTP with optionally STARTTLS when supported by the server. Not suitable for production use: vulnerable to a man-in-the-middle attack |
+    ///      <td>required</td>
-    /// | `smtp`  | unset                 | `smtp://user:pass@hostname:port`                   | 587          | Always unencrypted SMTP. Not suitable for production use: sends all data unencrypted                                                  |
+    ///      <td>smtp://smtp.example.com?tls=required</td>
-    ///
+    ///      <td>SMTP with STARTTLS required, when SMTP over TLS is not available</td>
-    /// IMPORTANT: some parameters like `user` and `pass` cannot simply
+    ///     </tr>
-    /// be concatenated to construct the final URL because special characters
+    ///     <tr>
-    /// contained within the parameter may confuse the URL decoder.
+    ///      <td>smtp</td>
-    /// Manually URL encode the parameters before concatenating them or use
+    ///      <td>opportunistic</td>
-    /// a proper URL encoder, like the following cargo script:
+    ///      <td>smtp://smtp.example.com?tls=opportunistic</td>
-    ///
+    ///      <td>
-    /// ```rust
+    ///         SMTP with optionally STARTTLS when supported by the server.
-    /// # let _ = r#"
+    ///         Caution: this method is vulnerable to a man-in-the-middle attack.
-    /// #!/usr/bin/env cargo
+    ///         Not recommended for production use.
-    ///
+    ///       </td>
-    /// //! ```cargo
+    ///     </tr>
-    /// //! [dependencies]
+    ///     <tr>
-    /// //! url = "2"
+    ///      <td>smtp</td>
-    /// //! ```
+    ///      <td>-</td>
-    /// # "#;
+    ///      <td>smtp://smtp.example.com</td>
-    ///
+    ///      <td>Unencrypted SMTP, not recommended for production use.</td>
-    /// use url::Url;
+    ///     </tr>
-    ///
+    ///   </tbody>
-    /// fn main() {
+    /// </table>
    ///     // don't touch this line
    ///     let mut url = Url::parse("foo://bar").unwrap();
    ///
    ///     // configure the scheme (`smtp` or `smtps`) here.
    ///     url.set_scheme("smtps").unwrap();
    ///     // configure the username and password.
    ///     // remove the following two lines if unauthenticated.
    ///     url.set_username("username").unwrap();
    ///     url.set_password(Some("password")).unwrap();
    ///     // configure the hostname
    ///     url.set_host(Some("smtp.example.com")).unwrap();
    ///     // configure the port - only necessary if using a non-default port
    ///     url.set_port(Some(465)).unwrap();
    ///     // configure the EHLO name
    ///     url.set_path("ehlo-name");
    ///
    ///     println!("{url}");
    /// }
    /// ```
    ///
    /// The connection URL can then be used in the following way:
    ///
    /// ```rust,no_run
    /// use lettre::{
@@ -280,11 +234,15 @@ where
    /// let mailer: AsyncSmtpTransport<Tokio1Executor> =
    ///     AsyncSmtpTransport::<Tokio1Executor>::from_url(
    ///         "smtps://username:password@smtp.example.com:465",
-    ///     )?
+    ///     )
    ///     .unwrap()
    ///     .build();
    ///
    /// // Send the email
-    /// mailer.send(email).await?;
+    /// match mailer.send(email).await {
    ///     Ok(_) => println!("Email sent successfully!"),
    ///     Err(e) => panic!("Could not send email: {e:?}"),
    /// }
    /// # Ok(())
    /// # }
    /// ```
@@ -367,7 +325,7 @@ impl AsyncSmtpTransportBuilder {
        self
    }
-    /// Set the authentication credentials to use
+    /// Set the authentication mechanism to use
    pub fn credentials(mut self, credentials: Credentials) -> Self {
        self.info.credentials = Some(credentials);
        self
@@ -380,17 +338,6 @@ impl AsyncSmtpTransportBuilder {
    }
    /// Set the port to use
    ///
    /// # ⚠️⚠️⚠️ You probably don't need to call this method ⚠️⚠️⚠️
    ///
    /// lettre usually picks the correct `port` when building
    /// [`AsyncSmtpTransport`] using [`AsyncSmtpTransport::relay`] or
    /// [`AsyncSmtpTransport::starttls_relay`].
    ///
    /// # Errors
    ///
    /// Using the incorrect `port` and [`Self::tls`] combination may
    /// lead to hard to debug IO errors coming from the TLS library.
    pub fn port(mut self, port: u16) -> Self {
        self.info.port = port;
        self
@@ -403,20 +350,10 @@ impl AsyncSmtpTransportBuilder {
    }
    /// Set the TLS settings to use
    ///
    /// # ⚠️⚠️⚠️ You probably don't need to call this method ⚠️⚠️⚠️
    ///
    /// By default lettre chooses the correct `tls` configuration when
    /// building [`AsyncSmtpTransport`] using [`AsyncSmtpTransport::relay`] or
    /// [`AsyncSmtpTransport::starttls_relay`].
    ///
    /// # Errors
    ///
    /// Using the incorrect [`Tls`] and [`Self::port`] combination may
    /// lead to hard to debug IO errors coming from the TLS library.
    #[cfg(any(
        feature = "tokio1-native-tls",
        feature = "tokio1-rustls-tls",
        feature = "async-std1-native-tls",
        feature = "async-std1-rustls-tls"
    ))]
    #[cfg_attr(
@@ -427,7 +364,7 @@ impl AsyncSmtpTransportBuilder {
            feature = "async-std1-rustls-tls"
        )))
    )]
-    pub fn tls(mut self, tls: Tls) -> Self {
+    pub fn tls(mut self, tls: super::Tls) -> Self {
        self.info.tls = tls;
        self
    }
--- a/src/transport/smtp/authentication.rs
+++ b/src/transport/smtp/authentication.rs
@@ -98,17 +98,13 @@ impl Mechanism {
                let decoded_challenge = challenge
                    .ok_or_else(|| error::client("This mechanism does expect a challenge"))?;
-                if contains_ignore_ascii_case(
+                if ["User Name", "Username:", "Username", "User Name\0"]
-                    decoded_challenge,
+                    .contains(&decoded_challenge)
-                    ["User Name", "Username:", "Username", "User Name\0"],
+                {
                ) {
                    return Ok(credentials.authentication_identity.clone());
                }
-                if contains_ignore_ascii_case(
+                if ["Password", "Password:", "Password\0"].contains(&decoded_challenge) {
                    decoded_challenge,
                    ["Password", "Password:", "Password\0"],
                ) {
                    return Ok(credentials.secret.clone());
                }
@@ -125,15 +121,6 @@ impl Mechanism {
    }
 }
 fn contains_ignore_ascii_case<'a>(
    haystack: &str,
    needles: impl IntoIterator<Item = &'a str>,
 ) -> bool {
    needles
        .into_iter()
        .any(|item| item.eq_ignore_ascii_case(haystack))
 }
 #[cfg(test)]
 mod test {
    use super::{Credentials, Mechanism};
@@ -168,23 +155,6 @@ mod test {
        assert!(mechanism.response(&credentials, None).is_err());
    }
    #[test]
    fn test_login_case_insensitive() {
        let mechanism = Mechanism::Login;
        let credentials = Credentials::new("alice".to_owned(), "wonderland".to_owned());
        assert_eq!(
            mechanism.response(&credentials, Some("username")).unwrap(),
            "alice"
        );
        assert_eq!(
            mechanism.response(&credentials, Some("password")).unwrap(),
            "wonderland"
        );
        assert!(mechanism.response(&credentials, None).is_err());
    }
    #[test]
    fn test_xoauth2() {
        let mechanism = Mechanism::Xoauth2;
--- a/src/transport/smtp/client/async_connection.rs
+++ b/src/transport/smtp/client/async_connection.rs
@@ -6,7 +6,7 @@ use futures_util::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
 use super::async_net::AsyncTokioStream;
 #[cfg(feature = "tracing")]
 use super::escape_crlf;
-use super::{AsyncNetworkStream, ClientCodec, TlsParameters};
+use super::{AsyncNetworkStream, ClientCodec, ConnectionState, TlsParameters};
 use crate::{
    transport::smtp::{
        authentication::{Credentials, Mechanism},
@@ -19,25 +19,11 @@ use crate::{
    Envelope,
 };
 macro_rules! try_smtp (
    ($err: expr, $client: ident) => ({
        match $err {
            Ok(val) => val,
            Err(err) => {
                $client.abort().await;
                return Err(From::from(err))
            },
        }
    })
 );
 /// Structure that implements the SMTP client
 pub struct AsyncSmtpConnection {
    /// TCP stream between client and server
    /// Value is None before connection
    stream: BufReader<AsyncNetworkStream>,
    /// Panic state
    panic: bool,
    /// Information about the server
    server_info: ServerInfo,
 }
@@ -86,7 +72,8 @@ impl AsyncSmtpConnection {
    ///     Some(TlsParameters::new("example.com".to_owned())?),
    ///     None,
    /// )
-    /// .await?;
+    /// .await
    /// .unwrap();
    /// # Ok(())
    /// # }
    /// ```
@@ -125,7 +112,6 @@ impl AsyncSmtpConnection {
        let stream = BufReader::new(stream);
        let mut conn = AsyncSmtpConnection {
            stream,
            panic: false,
            server_info: ServerInfo::default(),
        };
        // TODO log
@@ -169,30 +155,26 @@ impl AsyncSmtpConnection {
            mail_options.push(MailParameter::Body(MailBodyParameter::EightBitMime));
        }
-        try_smtp!(
+        self.command(Mail::new(envelope.from().cloned(), mail_options))
-            self.command(Mail::new(envelope.from().cloned(), mail_options))
+            .await?;
                .await,
            self
        );
        // Recipient
        for to_address in envelope.to() {
-            try_smtp!(
+            self.command(Rcpt::new(to_address.clone(), vec![])).await?;
                self.command(Rcpt::new(to_address.clone(), vec![])).await,
                self
            );
        }
        // Data
-        try_smtp!(self.command(Data).await, self);
+        self.command(Data).await?;
        // Message content
-        let result = try_smtp!(self.message(email).await, self);
+        self.message(email).await
        Ok(result)
    }
    pub fn has_broken(&self) -> bool {
-        self.panic
+        match self.stream.get_ref().state() {
            ConnectionState::Ok => false,
            ConnectionState::Broken | ConnectionState::Closed => true,
        }
    }
    pub fn can_starttls(&self) -> bool {
@@ -207,18 +189,20 @@ impl AsyncSmtpConnection {
    /// [rfc8314]: https://www.rfc-editor.org/rfc/rfc8314
    #[allow(unused_variables)]
    pub async fn starttls(
-        &mut self,
+        mut self,
        tls_parameters: TlsParameters,
        hello_name: &ClientId,
-    ) -> Result<(), Error> {
+    ) -> Result<Self, Error> {
        if self.server_info.supports_feature(Extension::StartTls) {
-            try_smtp!(self.command(Starttls).await, self);
+            self.command(Starttls).await?;
-            self.stream.get_mut().upgrade_tls(tls_parameters).await?;
+            let stream = self.stream.into_inner();
            let stream = stream.upgrade_tls(tls_parameters).await?;
            self.stream = BufReader::new(stream);
            #[cfg(feature = "tracing")]
            tracing::debug!("connection encrypted");
            // Send EHLO again
-            try_smtp!(self.ehlo(hello_name).await, self);
+            self.ehlo(hello_name).await?;
-            Ok(())
+            Ok(self)
        } else {
            Err(error::client("STARTTLS is not supported on this server"))
        }
@@ -226,22 +210,24 @@ impl AsyncSmtpConnection {
    /// Send EHLO and update server info
    async fn ehlo(&mut self, hello_name: &ClientId) -> Result<(), Error> {
-        let ehlo_response = try_smtp!(self.command(Ehlo::new(hello_name.clone())).await, self);
+        let ehlo_response = self.command(Ehlo::new(hello_name.clone())).await?;
-        self.server_info = try_smtp!(ServerInfo::from_response(&ehlo_response), self);
+        self.server_info = ServerInfo::from_response(&ehlo_response)?;
        Ok(())
    }
    pub async fn quit(&mut self) -> Result<Response, Error> {
-        Ok(try_smtp!(self.command(Quit).await, self))
+        self.command(Quit).await
    }
    pub async fn abort(&mut self) {
-        // Only try to quit if we are not already broken
+        match self.stream.get_ref().state() {
-        if !self.panic {
+            ConnectionState::Ok | ConnectionState::Broken => {
-            self.panic = true;
+                let _ = self.command(Quit).await;
-            let _ = self.command(Quit).await;
+                let _ = self.stream.close().await;
                self.stream.get_mut().set_state(ConnectionState::Closed);
            }
            ConnectionState::Closed => {}
        }
        let _ = self.stream.close().await;
    }
    /// Sets the underlying stream
@@ -278,15 +264,13 @@ impl AsyncSmtpConnection {
        while challenges > 0 && response.has_code(334) {
            challenges -= 1;
-            response = try_smtp!(
+            response = self
-                self.command(Auth::new_from_response(
+                .command(Auth::new_from_response(
                    mechanism,
                    credentials.clone(),
                    &response,
                )?)
-                .await,
+                .await?;
                self
            );
        }
        if challenges == 0 {
@@ -314,6 +298,9 @@ impl AsyncSmtpConnection {
    /// Writes a string to the server
    async fn write(&mut self, string: &[u8]) -> Result<(), Error> {
        self.stream.get_ref().state().verify()?;
        self.stream.get_mut().set_state(ConnectionState::Broken);
        self.stream
            .get_mut()
            .write_all(string)
@@ -325,6 +312,8 @@ impl AsyncSmtpConnection {
            .await
            .map_err(error::network)?;
        self.stream.get_mut().set_state(ConnectionState::Ok);
        #[cfg(feature = "tracing")]
        tracing::debug!("Wrote: {}", escape_crlf(&String::from_utf8_lossy(string)));
        Ok(())
@@ -332,6 +321,9 @@ impl AsyncSmtpConnection {
    /// Gets the SMTP response
    pub async fn read_response(&mut self) -> Result<Response, Error> {
        self.stream.get_ref().state().verify()?;
        self.stream.get_mut().set_state(ConnectionState::Broken);
        let mut buffer = String::with_capacity(100);
        while self
@@ -345,6 +337,8 @@ impl AsyncSmtpConnection {
            tracing::debug!("<< {}", escape_crlf(&buffer));
            match parse_response(&buffer) {
                Ok((_remaining, response)) => {
                    self.stream.get_mut().set_state(ConnectionState::Ok);
                    return if response.is_positive() {
                        Ok(response)
                    } else {
@@ -352,7 +346,7 @@ impl AsyncSmtpConnection {
                            response.code(),
                            Some(response.message().collect()),
                        ))
-                    }
+                    };
                }
                Err(nom::Err::Failure(e)) => {
                    return Err(error::response(e.to_string()));
@@ -372,10 +366,4 @@ impl AsyncSmtpConnection {
    pub fn peer_certificate(&self) -> Result<Vec<u8>, Error> {
        self.stream.get_ref().peer_certificate()
    }
    /// All the X509 certificates of the chain (DER encoded)
    #[cfg(any(feature = "rustls-tls", feature = "boring-tls"))]
    pub fn certificate_chain(&self) -> Result<Vec<Vec<u8>>, Error> {
        self.stream.get_ref().certificate_chain()
    }
 }
--- a/src/transport/smtp/client/async_net.rs
+++ b/src/transport/smtp/client/async_net.rs
@@ -6,11 +6,12 @@ use std::{
    time::Duration,
 };
 #[cfg(feature = "async-std1-native-tls")]
 use async_native_tls::TlsStream as AsyncStd1TlsStream;
 #[cfg(feature = "async-std1")]
 use async_std::net::{TcpStream as AsyncStd1TcpStream, ToSocketAddrs as AsyncStd1ToSocketAddrs};
 use futures_io::{
-    AsyncRead as FuturesAsyncRead, AsyncWrite as FuturesAsyncWrite, Error as IoError, ErrorKind,
+    AsyncRead as FuturesAsyncRead, AsyncWrite as FuturesAsyncWrite, Result as IoResult,
    Result as IoResult,
 };
 #[cfg(feature = "async-std1-rustls-tls")]
 use futures_rustls::client::TlsStream as AsyncStd1RustlsTlsStream;
@@ -34,10 +35,11 @@ use tokio1_rustls::client::TlsStream as Tokio1RustlsTlsStream;
    feature = "tokio1-native-tls",
    feature = "tokio1-rustls-tls",
    feature = "tokio1-boring-tls",
    feature = "async-std1-native-tls",
    feature = "async-std1-rustls-tls"
 ))]
 use super::InnerTlsParameters;
-use super::TlsParameters;
+use super::{ConnectionState, TlsParameters};
 #[cfg(feature = "tokio1")]
 use crate::transport::smtp::client::net::resolved_address_filter;
 use crate::transport::smtp::{error, Error};
@@ -46,6 +48,7 @@ use crate::transport::smtp::{error, Error};
 #[derive(Debug)]
 pub struct AsyncNetworkStream {
    inner: InnerAsyncNetworkStream,
    state: ConnectionState,
 }
 #[cfg(feature = "tokio1")]
@@ -83,19 +86,27 @@ enum InnerAsyncNetworkStream {
    #[cfg(feature = "async-std1")]
    AsyncStd1Tcp(AsyncStd1TcpStream),
    /// Encrypted Tokio 1.x TCP stream
    #[cfg(feature = "async-std1-native-tls")]
    AsyncStd1NativeTls(AsyncStd1TlsStream<AsyncStd1TcpStream>),
    /// Encrypted Tokio 1.x TCP stream
    #[cfg(feature = "async-std1-rustls-tls")]
    AsyncStd1RustlsTls(AsyncStd1RustlsTlsStream<AsyncStd1TcpStream>),
    /// Can't be built
    None,
 }
 impl AsyncNetworkStream {
    fn new(inner: InnerAsyncNetworkStream) -> Self {
-        if let InnerAsyncNetworkStream::None = inner {
+        AsyncNetworkStream {
-            debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
+            inner,
            state: ConnectionState::Ok,
        }
    }
-        AsyncNetworkStream { inner }
+    pub(super) fn state(&self) -> ConnectionState {
        self.state
    }
    pub(super) fn set_state(&mut self, state: ConnectionState) {
        self.state = state;
    }
    /// Returns peer's address
@@ -113,15 +124,10 @@ impl AsyncNetworkStream {
            InnerAsyncNetworkStream::Tokio1BoringTls(s) => s.get_ref().peer_addr(),
            #[cfg(feature = "async-std1")]
            InnerAsyncNetworkStream::AsyncStd1Tcp(s) => s.peer_addr(),
            #[cfg(feature = "async-std1-native-tls")]
            InnerAsyncNetworkStream::AsyncStd1NativeTls(s) => s.get_ref().peer_addr(),
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => s.get_ref().0.peer_addr(),
            InnerAsyncNetworkStream::None => {
                debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                Err(IoError::new(
                    ErrorKind::Other,
                    "InnerAsyncNetworkStream::None must never be built",
                ))
            }
        }
    }
@@ -170,7 +176,7 @@ impl AsyncNetworkStream {
                            last_err = Some(io::Error::new(
                                io::ErrorKind::TimedOut,
                                "connection timed out",
-                            ));
+                            ))
                        }
                    }
                } else {
@@ -191,7 +197,7 @@ impl AsyncNetworkStream {
        let mut stream =
            AsyncNetworkStream::new(InnerAsyncNetworkStream::Tokio1Tcp(Box::new(tcp_stream)));
        if let Some(tls_parameters) = tls_parameters {
-            stream.upgrade_tls(tls_parameters).await?;
+            stream = stream.upgrade_tls(tls_parameters).await?;
        }
        Ok(stream)
    }
@@ -222,7 +228,7 @@ impl AsyncNetworkStream {
                        last_err = Some(io::Error::new(
                            io::ErrorKind::TimedOut,
                            "connection timed out",
-                        ));
+                        ))
                    }
                }
            }
@@ -242,13 +248,13 @@ impl AsyncNetworkStream {
        let mut stream = AsyncNetworkStream::new(InnerAsyncNetworkStream::AsyncStd1Tcp(tcp_stream));
        if let Some(tls_parameters) = tls_parameters {
-            stream.upgrade_tls(tls_parameters).await?;
+            stream = stream.upgrade_tls(tls_parameters).await?;
        }
        Ok(stream)
    }
-    pub async fn upgrade_tls(&mut self, tls_parameters: TlsParameters) -> Result<(), Error> {
+    pub async fn upgrade_tls(self, tls_parameters: TlsParameters) -> Result<Self, Error> {
-        match &self.inner {
+        match self.inner {
            #[cfg(all(
                feature = "tokio1",
                not(any(
@@ -267,38 +273,35 @@ impl AsyncNetworkStream {
                feature = "tokio1-rustls-tls",
                feature = "tokio1-boring-tls"
            ))]
-            InnerAsyncNetworkStream::Tokio1Tcp(_) => {
+            InnerAsyncNetworkStream::Tokio1Tcp(tcp_stream) => {
-                // get owned TcpStream
+                let inner = Self::upgrade_tokio1_tls(tcp_stream, tls_parameters)
                let tcp_stream = mem::replace(&mut self.inner, InnerAsyncNetworkStream::None);
                let InnerAsyncNetworkStream::Tokio1Tcp(tcp_stream) = tcp_stream else {
                    unreachable!()
                };
                self.inner = Self::upgrade_tokio1_tls(tcp_stream, tls_parameters)
                    .await
                    .map_err(error::connection)?;
-                Ok(())
+                Ok(Self {
                    inner,
                    state: ConnectionState::Ok,
                })
            }
-            #[cfg(all(feature = "async-std1", not(feature = "async-std1-rustls-tls")))]
+            #[cfg(all(
                feature = "async-std1",
                not(any(feature = "async-std1-native-tls", feature = "async-std1-rustls-tls"))
            ))]
            InnerAsyncNetworkStream::AsyncStd1Tcp(_) => {
                let _ = tls_parameters;
-                panic!("Trying to upgrade an AsyncNetworkStream without having enabled the async-std1-rustls-tls feature");
+                panic!("Trying to upgrade an AsyncNetworkStream without having enabled either the async-std1-native-tls or the async-std1-rustls-tls feature");
            }
-            #[cfg(feature = "async-std1-rustls-tls")]
+            #[cfg(any(feature = "async-std1-native-tls", feature = "async-std1-rustls-tls"))]
-            InnerAsyncNetworkStream::AsyncStd1Tcp(_) => {
+            InnerAsyncNetworkStream::AsyncStd1Tcp(tcp_stream) => {
-                // get owned TcpStream
+                let inner = Self::upgrade_asyncstd1_tls(tcp_stream, tls_parameters)
                let tcp_stream = mem::replace(&mut self.inner, InnerAsyncNetworkStream::None);
                let InnerAsyncNetworkStream::AsyncStd1Tcp(tcp_stream) = tcp_stream else {
                    unreachable!()
                };
                self.inner = Self::upgrade_asyncstd1_tls(tcp_stream, tls_parameters)
                    .await
                    .map_err(error::connection)?;
-                Ok(())
+                Ok(Self {
                    inner,
                    state: ConnectionState::Ok,
                })
            }
-            _ => Ok(()),
+            _ => Ok(self),
        }
    }
@@ -372,7 +375,11 @@ impl AsyncNetworkStream {
    }
    #[allow(unused_variables)]
-    #[cfg(feature = "async-std1-rustls-tls")]
+    #[cfg(any(
        feature = "async-std1-native-tls",
        feature = "async-std1-rustls-tls",
        feature = "async-std1-boring-tls"
    ))]
    async fn upgrade_asyncstd1_tls(
        tcp_stream: AsyncStd1TcpStream,
        mut tls_parameters: TlsParameters,
@@ -383,6 +390,22 @@ impl AsyncNetworkStream {
            #[cfg(feature = "native-tls")]
            InnerTlsParameters::NativeTls(connector) => {
                panic!("native-tls isn't supported with async-std yet. See https://github.com/lettre/lettre/pull/531#issuecomment-757893531");
                /*
                #[cfg(not(feature = "async-std1-native-tls"))]
                panic!("built without the async-std1-native-tls feature");
                #[cfg(feature = "async-std1-native-tls")]
                return {
                    use async_native_tls::TlsConnector;
                    // TODO: fix
                    let connector: TlsConnector = todo!();
                    // let connector = TlsConnector::from(connector);
                    let stream = connector.connect(&domain, tcp_stream).await?;
                    Ok(InnerAsyncNetworkStream::AsyncStd1NativeTls(stream))
                };
                */
            }
            #[cfg(feature = "rustls-tls")]
            InnerTlsParameters::RustlsTls(config) => {
@@ -423,51 +446,10 @@ impl AsyncNetworkStream {
            InnerAsyncNetworkStream::Tokio1BoringTls(_) => true,
            #[cfg(feature = "async-std1")]
            InnerAsyncNetworkStream::AsyncStd1Tcp(_) => false,
            #[cfg(feature = "async-std1-native-tls")]
            InnerAsyncNetworkStream::AsyncStd1NativeTls(_) => true,
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(_) => true,
            InnerAsyncNetworkStream::None => false,
        }
    }
    pub fn certificate_chain(&self) -> Result<Vec<Vec<u8>>, Error> {
        match &self.inner {
            #[cfg(feature = "tokio1")]
            InnerAsyncNetworkStream::Tokio1Tcp(_) => {
                Err(error::client("Connection is not encrypted"))
            }
            #[cfg(feature = "tokio1-native-tls")]
            InnerAsyncNetworkStream::Tokio1NativeTls(_) => panic!("Unsupported"),
            #[cfg(feature = "tokio1-rustls-tls")]
            InnerAsyncNetworkStream::Tokio1RustlsTls(stream) => Ok(stream
                .get_ref()
                .1
                .peer_certificates()
                .unwrap()
                .iter()
                .map(|c| c.to_vec())
                .collect()),
            #[cfg(feature = "tokio1-boring-tls")]
            InnerAsyncNetworkStream::Tokio1BoringTls(stream) => Ok(stream
                .ssl()
                .peer_cert_chain()
                .unwrap()
                .iter()
                .map(|c| c.to_der().map_err(error::tls))
                .collect::<Result<Vec<_>, _>>()?),
            #[cfg(feature = "async-std1")]
            InnerAsyncNetworkStream::AsyncStd1Tcp(_) => {
                Err(error::client("Connection is not encrypted"))
            }
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(stream) => Ok(stream
                .get_ref()
                .1
                .peer_certificates()
                .unwrap()
                .iter()
                .map(|c| c.to_vec())
                .collect()),
            InnerAsyncNetworkStream::None => panic!("InnerNetworkStream::None must never be built"),
        }
    }
@@ -505,6 +487,8 @@ impl AsyncNetworkStream {
            InnerAsyncNetworkStream::AsyncStd1Tcp(_) => {
                Err(error::client("Connection is not encrypted"))
            }
            #[cfg(feature = "async-std1-native-tls")]
            InnerAsyncNetworkStream::AsyncStd1NativeTls(t) => panic!("Unsupported"),
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(stream) => Ok(stream
                .get_ref()
@@ -514,7 +498,6 @@ impl AsyncNetworkStream {
                .first()
                .unwrap()
                .to_vec()),
            InnerAsyncNetworkStream::None => panic!("InnerNetworkStream::None must never be built"),
        }
    }
 }
@@ -564,12 +547,10 @@ impl FuturesAsyncRead for AsyncNetworkStream {
            }
            #[cfg(feature = "async-std1")]
            InnerAsyncNetworkStream::AsyncStd1Tcp(s) => Pin::new(s).poll_read(cx, buf),
            #[cfg(feature = "async-std1-native-tls")]
            InnerAsyncNetworkStream::AsyncStd1NativeTls(s) => Pin::new(s).poll_read(cx, buf),
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_read(cx, buf),
            InnerAsyncNetworkStream::None => {
                debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                Poll::Ready(Ok(0))
            }
        }
    }
 }
@@ -591,12 +572,10 @@ impl FuturesAsyncWrite for AsyncNetworkStream {
            InnerAsyncNetworkStream::Tokio1BoringTls(s) => Pin::new(s).poll_write(cx, buf),
            #[cfg(feature = "async-std1")]
            InnerAsyncNetworkStream::AsyncStd1Tcp(s) => Pin::new(s).poll_write(cx, buf),
            #[cfg(feature = "async-std1-native-tls")]
            InnerAsyncNetworkStream::AsyncStd1NativeTls(s) => Pin::new(s).poll_write(cx, buf),
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_write(cx, buf),
            InnerAsyncNetworkStream::None => {
                debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                Poll::Ready(Ok(0))
            }
        }
    }
@@ -612,16 +591,16 @@ impl FuturesAsyncWrite for AsyncNetworkStream {
            InnerAsyncNetworkStream::Tokio1BoringTls(s) => Pin::new(s).poll_flush(cx),
            #[cfg(feature = "async-std1")]
            InnerAsyncNetworkStream::AsyncStd1Tcp(s) => Pin::new(s).poll_flush(cx),
            #[cfg(feature = "async-std1-native-tls")]
            InnerAsyncNetworkStream::AsyncStd1NativeTls(s) => Pin::new(s).poll_flush(cx),
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_flush(cx),
            InnerAsyncNetworkStream::None => {
                debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                Poll::Ready(Ok(()))
            }
        }
    }
    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<IoResult<()>> {
        self.state = ConnectionState::Closed;
        match &mut self.inner {
            #[cfg(feature = "tokio1")]
            InnerAsyncNetworkStream::Tokio1Tcp(s) => Pin::new(s).poll_shutdown(cx),
@@ -633,12 +612,10 @@ impl FuturesAsyncWrite for AsyncNetworkStream {
            InnerAsyncNetworkStream::Tokio1BoringTls(s) => Pin::new(s).poll_shutdown(cx),
            #[cfg(feature = "async-std1")]
            InnerAsyncNetworkStream::AsyncStd1Tcp(s) => Pin::new(s).poll_close(cx),
            #[cfg(feature = "async-std1-native-tls")]
            InnerAsyncNetworkStream::AsyncStd1NativeTls(s) => Pin::new(s).poll_close(cx),
            #[cfg(feature = "async-std1-rustls-tls")]
            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_close(cx),
            InnerAsyncNetworkStream::None => {
                debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                Poll::Ready(Ok(()))
            }
        }
    }
 }
--- a/src/transport/smtp/client/connection.rs
+++ b/src/transport/smtp/client/connection.rs
@@ -7,7 +7,7 @@ use std::{
 #[cfg(feature = "tracing")]
 use super::escape_crlf;
-use super::{ClientCodec, NetworkStream, TlsParameters};
+use super::{ClientCodec, ConnectionState, NetworkStream, TlsParameters};
 use crate::{
    address::Envelope,
    transport::smtp::{
@@ -20,25 +20,11 @@ use crate::{
    },
 };
 macro_rules! try_smtp (
    ($err: expr, $client: ident) => ({
        match $err {
            Ok(val) => val,
            Err(err) => {
                $client.abort();
                return Err(From::from(err))
            },
        }
    })
 );
 /// Structure that implements the SMTP client
 pub struct SmtpConnection {
    /// TCP stream between client and server
    /// Value is None before connection
    stream: BufReader<NetworkStream>,
    /// Panic state
    panic: bool,
    /// Information about the server
    server_info: ServerInfo,
 }
@@ -65,7 +51,6 @@ impl SmtpConnection {
        let stream = BufReader::new(stream);
        let mut conn = SmtpConnection {
            stream,
            panic: false,
            server_info: ServerInfo::default(),
        };
        conn.set_timeout(timeout).map_err(error::network)?;
@@ -110,26 +95,25 @@ impl SmtpConnection {
            mail_options.push(MailParameter::Body(MailBodyParameter::EightBitMime));
        }
-        try_smtp!(
+        self.command(Mail::new(envelope.from().cloned(), mail_options))?;
            self.command(Mail::new(envelope.from().cloned(), mail_options)),
            self
        );
        // Recipient
        for to_address in envelope.to() {
-            try_smtp!(self.command(Rcpt::new(to_address.clone(), vec![])), self);
+            self.command(Rcpt::new(to_address.clone(), vec![]))?;
        }
        // Data
-        try_smtp!(self.command(Data), self);
+        self.command(Data)?;
        // Message content
-        let result = try_smtp!(self.message(email), self);
+        self.message(email)
        Ok(result)
    }
    pub fn has_broken(&self) -> bool {
-        self.panic
+        match self.stream.get_ref().state() {
            ConnectionState::Ok => false,
            ConnectionState::Broken | ConnectionState::Closed => true,
        }
    }
    pub fn can_starttls(&self) -> bool {
@@ -138,20 +122,22 @@ impl SmtpConnection {
    #[allow(unused_variables)]
    pub fn starttls(
-        &mut self,
+        mut self,
        tls_parameters: &TlsParameters,
        hello_name: &ClientId,
-    ) -> Result<(), Error> {
+    ) -> Result<Self, Error> {
        if self.server_info.supports_feature(Extension::StartTls) {
            #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
            {
-                try_smtp!(self.command(Starttls), self);
+                self.command(Starttls)?;
-                self.stream.get_mut().upgrade_tls(tls_parameters)?;
+                let stream = self.stream.into_inner();
                let stream = stream.upgrade_tls(tls_parameters)?;
                self.stream = BufReader::new(stream);
                #[cfg(feature = "tracing")]
                tracing::debug!("connection encrypted");
                // Send EHLO again
-                try_smtp!(self.ehlo(hello_name), self);
+                self.ehlo(hello_name)?;
-                Ok(())
+                Ok(self)
            }
            #[cfg(not(any(
                feature = "native-tls",
@@ -168,22 +154,24 @@ impl SmtpConnection {
    /// Send EHLO and update server info
    fn ehlo(&mut self, hello_name: &ClientId) -> Result<(), Error> {
-        let ehlo_response = try_smtp!(self.command(Ehlo::new(hello_name.clone())), self);
+        let ehlo_response = self.command(Ehlo::new(hello_name.clone()))?;
-        self.server_info = try_smtp!(ServerInfo::from_response(&ehlo_response), self);
+        self.server_info = ServerInfo::from_response(&ehlo_response)?;
        Ok(())
    }
    pub fn quit(&mut self) -> Result<Response, Error> {
-        Ok(try_smtp!(self.command(Quit), self))
+        self.command(Quit)
    }
    pub fn abort(&mut self) {
-        // Only try to quit if we are not already broken
+        match self.stream.get_ref().state() {
-        if !self.panic {
+            ConnectionState::Ok | ConnectionState::Broken => {
-            self.panic = true;
+                let _ = self.command(Quit);
-            let _ = self.command(Quit);
+                let _ = self.stream.get_mut().shutdown(std::net::Shutdown::Both);
                self.stream.get_mut().set_state(ConnectionState::Closed);
            }
            ConnectionState::Closed => {}
        }
        let _ = self.stream.get_mut().shutdown(std::net::Shutdown::Both);
    }
    /// Sets the underlying stream
@@ -224,14 +212,11 @@ impl SmtpConnection {
        while challenges > 0 && response.has_code(334) {
            challenges -= 1;
-            response = try_smtp!(
+            response = self.command(Auth::new_from_response(
-                self.command(Auth::new_from_response(
+                mechanism,
-                    mechanism,
+                credentials.clone(),
-                    credentials.clone(),
+                &response,
-                    &response,
+            )?)?;
                )?),
                self
            );
        }
        if challenges == 0 {
@@ -260,12 +245,17 @@ impl SmtpConnection {
    /// Writes a string to the server
    fn write(&mut self, string: &[u8]) -> Result<(), Error> {
        self.stream.get_ref().state().verify()?;
        self.stream.get_mut().set_state(ConnectionState::Broken);
        self.stream
            .get_mut()
            .write_all(string)
            .map_err(error::network)?;
        self.stream.get_mut().flush().map_err(error::network)?;
        self.stream.get_mut().set_state(ConnectionState::Ok);
        #[cfg(feature = "tracing")]
        tracing::debug!("Wrote: {}", escape_crlf(&String::from_utf8_lossy(string)));
        Ok(())
@@ -273,6 +263,9 @@ impl SmtpConnection {
    /// Gets the SMTP response
    pub fn read_response(&mut self) -> Result<Response, Error> {
        self.stream.get_ref().state().verify()?;
        self.stream.get_mut().set_state(ConnectionState::Broken);
        let mut buffer = String::with_capacity(100);
        while self.stream.read_line(&mut buffer).map_err(error::network)? > 0 {
@@ -280,6 +273,8 @@ impl SmtpConnection {
            tracing::debug!("<< {}", escape_crlf(&buffer));
            match parse_response(&buffer) {
                Ok((_remaining, response)) => {
                    self.stream.get_mut().set_state(ConnectionState::Ok);
                    return if response.is_positive() {
                        Ok(response)
                    } else {
@@ -307,10 +302,4 @@ impl SmtpConnection {
    pub fn peer_certificate(&self) -> Result<Vec<u8>, Error> {
        self.stream.get_ref().peer_certificate()
    }
    /// All the X509 certificates of the chain (DER encoded)
    #[cfg(any(feature = "rustls-tls", feature = "boring-tls"))]
    pub fn certificate_chain(&self) -> Result<Vec<Vec<u8>>, Error> {
        self.stream.get_ref().certificate_chain()
    }
 }
--- a/src/transport/smtp/client/mod.rs
+++ b/src/transport/smtp/client/mod.rs
@@ -38,8 +38,9 @@ pub(super) use self::tls::InnerTlsParameters;
 pub use self::tls::TlsVersion;
 pub use self::{
    connection::SmtpConnection,
-    tls::{Certificate, CertificateStore, Identity, Tls, TlsParameters, TlsParametersBuilder},
+    tls::{Certificate, CertificateStore, Tls, TlsParameters, TlsParametersBuilder},
 };
 use super::{error, Error};
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 mod async_connection;
@@ -49,6 +50,23 @@ mod connection;
 mod net;
 mod tls;
 #[derive(Debug, Copy, Clone)]
 enum ConnectionState {
    Ok,
    Broken,
    Closed,
 }
 impl ConnectionState {
    fn verify(&mut self) -> Result<(), Error> {
        match self {
            Self::Ok => Ok(()),
            Self::Broken => Err(error::connection("connection broken")),
            Self::Closed => Err(error::connection("connection closed")),
        }
    }
 }
 /// The codec used for transparency
 #[derive(Debug)]
 struct ClientCodec {
@@ -139,7 +157,7 @@ mod test {
    }
    #[test]
-    #[cfg(feature = "tracing")]
+    #[cfg(feature = "log")]
    fn test_escape_crlf() {
        assert_eq!(escape_crlf("\r\n"), "<CRLF>");
        assert_eq!(escape_crlf("EHLO my_name\r\n"), "EHLO my_name<CRLF>");
--- a/src/transport/smtp/client/net.rs
+++ b/src/transport/smtp/client/net.rs
@@ -2,8 +2,7 @@
 use std::sync::Arc;
 use std::{
    io::{self, Read, Write},
-    mem,
+    net::{IpAddr, Shutdown, SocketAddr, TcpStream, ToSocketAddrs},
    net::{IpAddr, Ipv4Addr, Shutdown, SocketAddr, SocketAddrV4, TcpStream, ToSocketAddrs},
    time::Duration,
 };
@@ -17,12 +16,13 @@ use socket2::{Domain, Protocol, Type};
 #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
 use super::InnerTlsParameters;
-use super::TlsParameters;
+use super::{ConnectionState, TlsParameters};
 use crate::transport::smtp::{error, Error};
 /// A network stream
 pub struct NetworkStream {
    inner: InnerNetworkStream,
    state: ConnectionState,
 }
 /// Represents the different types of underlying network streams
@@ -40,17 +40,22 @@ enum InnerNetworkStream {
    RustlsTls(StreamOwned<ClientConnection, TcpStream>),
    #[cfg(feature = "boring-tls")]
    BoringTls(SslStream<TcpStream>),
    /// Can't be built
    None,
 }
 impl NetworkStream {
    fn new(inner: InnerNetworkStream) -> Self {
-        if let InnerNetworkStream::None = inner {
+        NetworkStream {
-            debug_assert!(false, "InnerNetworkStream::None must never be built");
+            inner,
            state: ConnectionState::Ok,
        }
    }
-        NetworkStream { inner }
+    pub(super) fn state(&self) -> ConnectionState {
        self.state
    }
    pub(super) fn set_state(&mut self, state: ConnectionState) {
        self.state = state;
    }
    /// Returns peer's address
@@ -63,18 +68,13 @@ impl NetworkStream {
            InnerNetworkStream::RustlsTls(s) => s.get_ref().peer_addr(),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(s) => s.get_ref().peer_addr(),
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                Ok(SocketAddr::V4(SocketAddrV4::new(
                    Ipv4Addr::new(127, 0, 0, 1),
                    80,
                )))
            }
        }
    }
    /// Shutdowns the connection
-    pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {
+    pub fn shutdown(&mut self, how: Shutdown) -> io::Result<()> {
        self.state = ConnectionState::Closed;
        match &self.inner {
            InnerNetworkStream::Tcp(s) => s.shutdown(how),
            #[cfg(feature = "native-tls")]
@@ -83,10 +83,6 @@ impl NetworkStream {
            InnerNetworkStream::RustlsTls(s) => s.get_ref().shutdown(how),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(s) => s.get_ref().shutdown(how),
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                Ok(())
            }
        }
    }
@@ -119,12 +115,12 @@ impl NetworkStream {
                if let Some(timeout) = timeout {
                    match socket.connect_timeout(&addr.into(), timeout) {
-                        Ok(()) => return Ok(socket.into()),
+                        Ok(_) => return Ok(socket.into()),
                        Err(err) => last_err = Some(err),
                    }
                } else {
                    match socket.connect(&addr.into()) {
-                        Ok(()) => return Ok(socket.into()),
+                        Ok(_) => return Ok(socket.into()),
                        Err(err) => last_err = Some(err),
                    }
                }
@@ -139,13 +135,13 @@ impl NetworkStream {
        let tcp_stream = try_connect(server, timeout, local_addr)?;
        let mut stream = NetworkStream::new(InnerNetworkStream::Tcp(tcp_stream));
        if let Some(tls_parameters) = tls_parameters {
-            stream.upgrade_tls(tls_parameters)?;
+            stream = stream.upgrade_tls(tls_parameters)?;
        }
        Ok(stream)
    }
-    pub fn upgrade_tls(&mut self, tls_parameters: &TlsParameters) -> Result<(), Error> {
+    pub fn upgrade_tls(self, tls_parameters: &TlsParameters) -> Result<Self, Error> {
-        match &self.inner {
+        match self.inner {
            #[cfg(not(any(
                feature = "native-tls",
                feature = "rustls-tls",
@@ -157,17 +153,14 @@ impl NetworkStream {
            }
            #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
-            InnerNetworkStream::Tcp(_) => {
+            InnerNetworkStream::Tcp(tcp_stream) => {
-                // get owned TcpStream
+                let inner = Self::upgrade_tls_impl(tcp_stream, tls_parameters)?;
-                let tcp_stream = mem::replace(&mut self.inner, InnerNetworkStream::None);
+                Ok(Self {
-                let InnerNetworkStream::Tcp(tcp_stream) = tcp_stream else {
+                    inner,
-                    unreachable!()
+                    state: ConnectionState::Ok,
-                };
+                })
                self.inner = Self::upgrade_tls_impl(tcp_stream, tls_parameters)?;
                Ok(())
            }
-            _ => Ok(()),
+            _ => Ok(self),
        }
    }
@@ -215,36 +208,6 @@ impl NetworkStream {
            InnerNetworkStream::RustlsTls(_) => true,
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(_) => true,
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                false
            }
        }
    }
    #[cfg(any(feature = "rustls-tls", feature = "boring-tls"))]
    pub fn certificate_chain(&self) -> Result<Vec<Vec<u8>>, Error> {
        match &self.inner {
            InnerNetworkStream::Tcp(_) => Err(error::client("Connection is not encrypted")),
            #[cfg(feature = "native-tls")]
            InnerNetworkStream::NativeTls(_) => panic!("Unsupported"),
            #[cfg(feature = "rustls-tls")]
            InnerNetworkStream::RustlsTls(stream) => Ok(stream
                .conn
                .peer_certificates()
                .unwrap()
                .iter()
                .map(|c| c.to_vec())
                .collect()),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(stream) => Ok(stream
                .ssl()
                .peer_cert_chain()
                .unwrap()
                .iter()
                .map(|c| c.to_der().map_err(error::tls))
                .collect::<Result<Vec<_>, _>>()?),
            InnerNetworkStream::None => panic!("InnerNetworkStream::None must never be built"),
        }
    }
@@ -274,7 +237,6 @@ impl NetworkStream {
                .unwrap()
                .to_der()
                .map_err(error::tls)?),
            InnerNetworkStream::None => panic!("InnerNetworkStream::None must never be built"),
        }
    }
@@ -287,10 +249,6 @@ impl NetworkStream {
            InnerNetworkStream::RustlsTls(stream) => stream.get_ref().set_read_timeout(duration),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(stream) => stream.get_ref().set_read_timeout(duration),
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                Ok(())
            }
        }
    }
@@ -305,10 +263,6 @@ impl NetworkStream {
            InnerNetworkStream::RustlsTls(stream) => stream.get_ref().set_write_timeout(duration),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(stream) => stream.get_ref().set_write_timeout(duration),
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                Ok(())
            }
        }
    }
 }
@@ -323,10 +277,6 @@ impl Read for NetworkStream {
            InnerNetworkStream::RustlsTls(s) => s.read(buf),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(s) => s.read(buf),
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                Ok(0)
            }
        }
    }
 }
@@ -341,10 +291,6 @@ impl Write for NetworkStream {
            InnerNetworkStream::RustlsTls(s) => s.write(buf),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(s) => s.write(buf),
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                Ok(0)
            }
        }
    }
@@ -357,10 +303,6 @@ impl Write for NetworkStream {
            InnerNetworkStream::RustlsTls(s) => s.flush(),
            #[cfg(feature = "boring-tls")]
            InnerNetworkStream::BoringTls(s) => s.flush(),
            InnerNetworkStream::None => {
                debug_assert!(false, "InnerNetworkStream::None must never be built");
                Ok(())
            }
        }
    }
 }
@@ -368,7 +310,7 @@ impl Write for NetworkStream {
 /// If the local address is set, binds the socket to this address.
 /// If local address is not set, then destination address is required to determine the default
 /// local address on some platforms.
-/// See: <https://github.com/hyperium/hyper/blob/faf24c6ad8eee1c3d5ccc9a4d4835717b8e2903f/src/client/connect/http.rs#L560>
+/// See: https://github.com/hyperium/hyper/blob/faf24c6ad8eee1c3d5ccc9a4d4835717b8e2903f/src/client/connect/http.rs#L560
 fn bind_local_address(
    socket: &socket2::Socket,
    dst_addr: &SocketAddr,
--- a/src/transport/smtp/client/tls.rs
+++ b/src/transport/smtp/client/tls.rs
@@ -4,7 +4,6 @@ use std::{io, sync::Arc};
 #[cfg(feature = "boring-tls")]
 use boring::{
    pkey::PKey,
    ssl::{SslConnector, SslVersion},
    x509::store::X509StoreBuilder,
 };
@@ -13,10 +12,8 @@ use native_tls::{Protocol, TlsConnector};
 #[cfg(feature = "rustls-tls")]
 use rustls::{
    client::danger::{HandshakeSignatureValid, ServerCertVerified, ServerCertVerifier},
    crypto::WebPkiSupportedAlgorithms,
    crypto::{verify_tls12_signature, verify_tls13_signature},
-    pki_types::{CertificateDer, PrivateKeyDer, ServerName, UnixTime},
+    pki_types::{CertificateDer, ServerName, UnixTime},
    server::ParsedCertificate,
    ClientConfig, DigitallySignedStruct, Error as TlsError, RootCertStore, SignatureScheme,
 };
@@ -59,61 +56,27 @@ pub enum TlsVersion {
    Tlsv13,
 }
-/// Specifies how to establish a TLS connection
+/// How to apply TLS to a client connection
 ///
 /// TLDR: Use [`Tls::Wrapper`] or [`Tls::Required`] when
 /// connecting to a remote server, [`Tls::None`] when
 /// connecting to a local server.
 #[derive(Clone)]
 #[allow(missing_copy_implementations)]
 pub enum Tls {
-    /// Insecure (plaintext) connection only.
+    /// Insecure connection only (for testing purposes)
    ///
    /// This option **always** uses a plaintext connection and should only
    /// be used for trusted local relays. It is **highly discouraged**
    /// for remote servers, as it exposes credentials and emails to potential
    /// interception.
    ///
    /// Note: Servers requiring credentials or emails to be sent over TLS
    /// may reject connections when this option is used.
    None,
-    /// Begin with a plaintext connection and attempt to use `STARTTLS` if available.
+    /// Start with insecure connection and use `STARTTLS` when available
    ///
    /// lettre will try to upgrade to a TLS-secured connection but will fall back
    /// to plaintext if the server does not support TLS. This option is provided for
    /// compatibility but is **strongly discouraged**, as it exposes connections to
    /// potential MITM (man-in-the-middle) attacks.
    ///
    /// Warning: A malicious intermediary could intercept the `STARTTLS` flag,
    /// causing lettre to believe the server only supports plaintext connections.
    #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
    #[cfg_attr(
        docsrs,
        doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
    )]
    Opportunistic(TlsParameters),
-    /// Begin with a plaintext connection and require `STARTTLS` for security.
+    /// Start with insecure connection and require `STARTTLS`
    ///
    /// lettre will upgrade plaintext TCP connections to TLS before transmitting
    /// any sensitive data. If the server does not support TLS, the connection
    /// attempt will fail, ensuring no credentials or emails are sent in plaintext.
    ///
    /// Unlike [`Tls::Opportunistic`], this option is secure against MITM attacks.
    /// For optimal security and performance, consider using [`Tls::Wrapper`] instead,
    /// as it requires fewer roundtrips to establish a secure connection.
    #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
    #[cfg_attr(
        docsrs,
        doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
    )]
    Required(TlsParameters),
-    /// Establish a connection wrapped in TLS from the start.
+    /// Use TLS wrapped connection
    ///
    /// lettre connects to the server and immediately performs a TLS handshake.
    /// If the handshake fails, the connection attempt is aborted without
    /// transmitting any sensitive data.
    ///
    /// This is the fastest and most secure option for establishing a connection.
    #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
    #[cfg_attr(
        docsrs,
@@ -145,7 +108,7 @@ pub enum CertificateStore {
    /// For native-tls, this will use the system certificate store on Windows, the keychain on
    /// macOS, and OpenSSL directories on Linux (usually `/etc/ssl`).
    ///
-    /// For rustls, this will also use the system store if the `rustls-native-certs` feature is
+    /// For rustls, this will also use the the system store if the `rustls-native-certs` feature is
    /// enabled, or will fall back to `webpki-roots`.
    ///
    /// The boring-tls backend uses the same logic as OpenSSL on all platforms.
@@ -176,7 +139,6 @@ pub struct TlsParametersBuilder {
    domain: String,
    cert_store: CertificateStore,
    root_certs: Vec<Certificate>,
    identity: Option<Identity>,
    accept_invalid_hostnames: bool,
    accept_invalid_certs: bool,
    #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
@@ -190,7 +152,6 @@ impl TlsParametersBuilder {
            domain,
            cert_store: CertificateStore::Default,
            root_certs: Vec::new(),
            identity: None,
            accept_invalid_hostnames: false,
            accept_invalid_certs: false,
            #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
@@ -206,20 +167,12 @@ impl TlsParametersBuilder {
    /// Add a custom root certificate
    ///
-    /// Can be used to safely connect to a server using a self-signed certificate, for example.
+    /// Can be used to safely connect to a server using a self signed certificate, for example.
    pub fn add_root_certificate(mut self, cert: Certificate) -> Self {
        self.root_certs.push(cert);
        self
    }
    /// Add a client certificate
    ///
    /// Can be used to configure a client certificate to present to the server.
    pub fn identify_with(mut self, identity: Identity) -> Self {
        self.identity = Some(identity);
        self
    }
    /// Controls whether certificates with an invalid hostname are accepted
    ///
    /// Defaults to `false`.
@@ -231,11 +184,10 @@ impl TlsParametersBuilder {
    /// including those from other sites, are trusted.
    ///
    /// This method introduces significant vulnerabilities to man-in-the-middle attacks.
-    #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
+    ///
-    #[cfg_attr(
+    /// Hostname verification can only be disabled with the `native-tls` TLS backend.
-        docsrs,
+    #[cfg(any(feature = "native-tls", feature = "boring-tls"))]
-        doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "native-tls", feature = "boring-tls"))))]
    )]
    pub fn dangerous_accept_invalid_hostnames(mut self, accept_invalid_hostnames: bool) -> Self {
        self.accept_invalid_hostnames = accept_invalid_hostnames;
        self
@@ -323,10 +275,6 @@ impl TlsParametersBuilder {
        };
        tls_builder.min_protocol_version(Some(min_tls_version));
        if let Some(identity) = self.identity {
            tls_builder.identity(identity.native_tls);
        }
        let connector = tls_builder.build().map_err(error::tls)?;
        Ok(TlsParameters {
            connector: InnerTlsParameters::NativeTls(connector),
@@ -369,15 +317,6 @@ impl TlsParametersBuilder {
            }
        }
        if let Some(identity) = self.identity {
            tls_builder
                .set_certificate(identity.boring_tls.0.as_ref())
                .map_err(error::tls)?;
            tls_builder
                .set_private_key(identity.boring_tls.1.as_ref())
                .map_err(error::tls)?;
        }
        let min_tls_version = match self.min_tls_version {
            TlsVersion::Tlsv10 => SslVersion::TLS1,
            TlsVersion::Tlsv11 => SslVersion::TLS1_1,
@@ -413,72 +352,51 @@ impl TlsParametersBuilder {
        };
        let tls = ClientConfig::builder_with_protocol_versions(supported_versions);
        let provider = rustls::crypto::CryptoProvider::get_default()
            .cloned()
            .unwrap_or_else(|| Arc::new(rustls::crypto::ring::default_provider()));
-        // Build TLS config
+        let tls = if self.accept_invalid_certs {
        let signature_algorithms = provider.signature_verification_algorithms;
        let mut root_cert_store = RootCertStore::empty();
        #[cfg(feature = "rustls-native-certs")]
        fn load_native_roots(store: &mut RootCertStore) {
            let rustls_native_certs::CertificateResult { certs, errors, .. } =
                rustls_native_certs::load_native_certs();
            let errors_len = errors.len();
            let (added, ignored) = store.add_parsable_certificates(certs);
            #[cfg(feature = "tracing")]
            tracing::debug!(
                "loaded platform certs with {errors_len} failing to load, {added} valid and {ignored} ignored (invalid) certs"
            );
        }
        #[cfg(feature = "rustls-tls")]
        fn load_webpki_roots(store: &mut RootCertStore) {
            store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
        }
        match self.cert_store {
            CertificateStore::Default => {
                #[cfg(feature = "rustls-native-certs")]
                load_native_roots(&mut root_cert_store);
                #[cfg(not(feature = "rustls-native-certs"))]
                load_webpki_roots(&mut root_cert_store);
            }
            #[cfg(feature = "rustls-tls")]
            CertificateStore::WebpkiRoots => {
                load_webpki_roots(&mut root_cert_store);
            }
            CertificateStore::None => {}
        }
        for cert in self.root_certs {
            for rustls_cert in cert.rustls {
                root_cert_store.add(rustls_cert).map_err(error::tls)?;
            }
        }
        let tls = if self.accept_invalid_certs || self.accept_invalid_hostnames {
            let verifier = InvalidCertsVerifier {
                ignore_invalid_hostnames: self.accept_invalid_hostnames,
                ignore_invalid_certs: self.accept_invalid_certs,
                roots: root_cert_store,
                signature_algorithms,
            };
            tls.dangerous()
-                .with_custom_certificate_verifier(Arc::new(verifier))
+                .with_custom_certificate_verifier(Arc::new(InvalidCertsVerifier {}))
        } else {
            let mut root_cert_store = RootCertStore::empty();
            #[cfg(feature = "rustls-native-certs")]
            fn load_native_roots(store: &mut RootCertStore) -> Result<(), Error> {
                let native_certs = rustls_native_certs::load_native_certs().map_err(error::tls)?;
                let (added, ignored) = store.add_parsable_certificates(native_certs);
                #[cfg(feature = "tracing")]
                tracing::debug!(
                    "loaded platform certs with {added} valid and {ignored} ignored (invalid) certs"
                );
                Ok(())
            }
            #[cfg(feature = "rustls-tls")]
            fn load_webpki_roots(store: &mut RootCertStore) {
                store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
            }
            match self.cert_store {
                CertificateStore::Default => {
                    #[cfg(feature = "rustls-native-certs")]
                    load_native_roots(&mut root_cert_store)?;
                    #[cfg(not(feature = "rustls-native-certs"))]
                    load_webpki_roots(&mut root_cert_store);
                }
                #[cfg(feature = "rustls-tls")]
                CertificateStore::WebpkiRoots => {
                    load_webpki_roots(&mut root_cert_store);
                }
                CertificateStore::None => {}
            }
            for cert in self.root_certs {
                for rustls_cert in cert.rustls {
                    root_cert_store.add(rustls_cert).map_err(error::tls)?;
                }
            }
            tls.with_root_certificates(root_cert_store)
        };
-
+        let tls = tls.with_no_client_auth();
        let tls = if let Some(identity) = self.identity {
            let (client_certificates, private_key) = identity.rustls_tls;
            tls.with_client_auth_cert(client_certificates, private_key)
                .map_err(error::tls)?
        } else {
            tls.with_no_client_auth()
        };
        Ok(TlsParameters {
            connector: InnerTlsParameters::RustlsTls(Arc::new(tls)),
@@ -543,7 +461,7 @@ impl TlsParameters {
    }
 }
-/// A certificate that can be used with [`TlsParametersBuilder::add_root_certificate`]
+/// A client certificate that can be used with [`TlsParametersBuilder::add_root_certificate`]
 #[derive(Clone)]
 #[allow(missing_copy_implementations)]
 pub struct Certificate {
@@ -610,110 +528,20 @@ impl Debug for Certificate {
    }
 }
 /// An identity that can be used with [`TlsParametersBuilder::identify_with`]
 #[allow(missing_copy_implementations)]
 pub struct Identity {
    #[cfg(feature = "native-tls")]
    native_tls: native_tls::Identity,
    #[cfg(feature = "rustls-tls")]
    rustls_tls: (Vec<CertificateDer<'static>>, PrivateKeyDer<'static>),
    #[cfg(feature = "boring-tls")]
    boring_tls: (boring::x509::X509, PKey<boring::pkey::Private>),
 }
 impl Debug for Identity {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Identity").finish()
    }
 }
 impl Clone for Identity {
    fn clone(&self) -> Self {
        Identity {
            #[cfg(feature = "native-tls")]
            native_tls: self.native_tls.clone(),
            #[cfg(feature = "rustls-tls")]
            rustls_tls: (self.rustls_tls.0.clone(), self.rustls_tls.1.clone_key()),
            #[cfg(feature = "boring-tls")]
            boring_tls: (self.boring_tls.0.clone(), self.boring_tls.1.clone()),
        }
    }
 }
 #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
 impl Identity {
    pub fn from_pem(pem: &[u8], key: &[u8]) -> Result<Self, Error> {
        Ok(Self {
            #[cfg(feature = "native-tls")]
            native_tls: Identity::from_pem_native_tls(pem, key)?,
            #[cfg(feature = "rustls-tls")]
            rustls_tls: Identity::from_pem_rustls_tls(pem, key)?,
            #[cfg(feature = "boring-tls")]
            boring_tls: Identity::from_pem_boring_tls(pem, key)?,
        })
    }
    #[cfg(feature = "native-tls")]
    fn from_pem_native_tls(pem: &[u8], key: &[u8]) -> Result<native_tls::Identity, Error> {
        native_tls::Identity::from_pkcs8(pem, key).map_err(error::tls)
    }
    #[cfg(feature = "rustls-tls")]
    fn from_pem_rustls_tls(
        pem: &[u8],
        mut key: &[u8],
    ) -> Result<(Vec<CertificateDer<'static>>, PrivateKeyDer<'static>), Error> {
        let key = rustls_pemfile::private_key(&mut key)
            .map_err(error::tls)?
            .ok_or_else(|| error::tls("no private key found"))?;
        Ok((vec![pem.to_owned().into()], key))
    }
    #[cfg(feature = "boring-tls")]
    fn from_pem_boring_tls(
        pem: &[u8],
        key: &[u8],
    ) -> Result<(boring::x509::X509, PKey<boring::pkey::Private>), Error> {
        let cert = boring::x509::X509::from_pem(pem).map_err(error::tls)?;
        let key = boring::pkey::PKey::private_key_from_pem(key).map_err(error::tls)?;
        Ok((cert, key))
    }
 }
 #[cfg(feature = "rustls-tls")]
 #[derive(Debug)]
-struct InvalidCertsVerifier {
+struct InvalidCertsVerifier;
    ignore_invalid_hostnames: bool,
    ignore_invalid_certs: bool,
    roots: RootCertStore,
    signature_algorithms: WebPkiSupportedAlgorithms,
 }
 #[cfg(feature = "rustls-tls")]
 impl ServerCertVerifier for InvalidCertsVerifier {
    fn verify_server_cert(
        &self,
-        end_entity: &CertificateDer<'_>,
+        _end_entity: &CertificateDer<'_>,
-        intermediates: &[CertificateDer<'_>],
+        _intermediates: &[CertificateDer<'_>],
-        server_name: &ServerName<'_>,
+        _server_name: &ServerName<'_>,
        _ocsp_response: &[u8],
-        now: UnixTime,
+        _now: UnixTime,
    ) -> Result<ServerCertVerified, TlsError> {
        let cert = ParsedCertificate::try_from(end_entity)?;
        if !self.ignore_invalid_certs {
            rustls::client::verify_server_cert_signed_by_trust_anchor(
                &cert,
                &self.roots,
                intermediates,
                now,
                self.signature_algorithms.all,
            )?;
        }
        if !self.ignore_invalid_hostnames {
            rustls::client::verify_server_name(&cert, server_name)?;
        }
        Ok(ServerCertVerified::assertion())
    }
--- a/src/transport/smtp/connection_url.rs
+++ b/src/transport/smtp/connection_url.rs
@@ -1,5 +1,3 @@
 use std::borrow::Cow;
 use url::Url;
 #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
@@ -64,7 +62,7 @@ impl TransportBuilder for AsyncSmtpTransportBuilder {
    }
 }
-/// Create a new `SmtpTransportBuilder` or `AsyncSmtpTransportBuilder` from a connection URL
+/// Create a new SmtpTransportBuilder or AsyncSmtpTransportBuilder from a connection URL
 pub(crate) fn from_connection_url<B: TransportBuilder>(connection_url: &str) -> Result<B, Error> {
    let connection_url = Url::parse(connection_url).map_err(error::connection)?;
    let tls: Option<String> = connection_url
@@ -86,26 +84,26 @@ pub(crate) fn from_connection_url<B: TransportBuilder>(connection_url: &str) ->
        ("smtp", Some("required")) => {
            builder = builder
                .port(connection_url.port().unwrap_or(SUBMISSION_PORT))
-                .tls(Tls::Required(TlsParameters::new(host.into())?));
+                .tls(Tls::Required(TlsParameters::new(host.into())?))
        }
        #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
        ("smtp", Some("opportunistic")) => {
            builder = builder
                .port(connection_url.port().unwrap_or(SUBMISSION_PORT))
-                .tls(Tls::Opportunistic(TlsParameters::new(host.into())?));
+                .tls(Tls::Opportunistic(TlsParameters::new(host.into())?))
        }
        #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
        ("smtps", _) => {
            builder = builder
                .port(connection_url.port().unwrap_or(SUBMISSIONS_PORT))
-                .tls(Tls::Wrapper(TlsParameters::new(host.into())?));
+                .tls(Tls::Wrapper(TlsParameters::new(host.into())?))
        }
        (scheme, tls) => {
            return Err(error::connection(format!(
                "Unknown scheme '{scheme}' or tls parameter '{tls:?}', note that a transport with TLS requires one of the TLS features"
            )))
        }
-    }
+    };
    // use the path segment of the URL as name in the name in the HELO / EHLO command
    if connection_url.path().len() > 1 {
@@ -117,7 +115,7 @@ pub(crate) fn from_connection_url<B: TransportBuilder>(connection_url: &str) ->
        let percent_decode = |s: &str| {
            percent_encoding::percent_decode_str(s)
                .decode_utf8()
-                .map(Cow::into_owned)
+                .map(|cow| cow.into_owned())
                .map_err(error::connection)
        };
        let credentials = Credentials::new(
--- a/src/transport/smtp/error.rs
+++ b/src/transport/smtp/error.rs
@@ -142,7 +142,7 @@ impl fmt::Display for Error {
            Kind::Permanent(code) => {
                write!(f, "permanent error ({code})")?;
            }
-        }
+        };
        if let Some(e) = &self.inner.source {
            write!(f, ": {e}")?;
--- a/src/transport/smtp/extension.rs
+++ b/src/transport/smtp/extension.rs
@@ -129,8 +129,9 @@ impl Display for ServerInfo {
 impl ServerInfo {
    /// Parses a EHLO response to create a `ServerInfo`
    pub fn from_response(response: &Response) -> Result<ServerInfo, Error> {
-        let Some(name) = response.first_word() else {
+        let name = match response.first_word() {
-            return Err(error::response("Could not read server name"));
+            Some(name) => name,
            None => return Err(error::response("Could not read server name")),
        };
        let mut features: HashSet<Extension> = HashSet::new();
@@ -168,7 +169,7 @@ impl ServerInfo {
                    }
                }
                _ => (),
-            }
+            };
        }
        Ok(ServerInfo {
@@ -290,8 +291,14 @@ impl Display for RcptParameter {
 #[cfg(test)]
 mod test {
    use std::collections::HashSet;
    use super::*;
-    use crate::transport::smtp::response::{Category, Code, Detail, Severity};
+    use crate::transport::smtp::{
        authentication::Mechanism,
        response::{Category, Code, Detail, Response, Severity},
    };
    #[test]
    fn test_clientid_fmt() {
--- a/src/transport/smtp/mod.rs
+++ b/src/transport/smtp/mod.rs
@@ -26,17 +26,43 @@
 //!
 //! The relay server can be the local email server, a specific host or a third-party service.
 //!
-//! #### Simple example with authentication
+//! #### Simple example
 //!
-//! A good starting point for sending emails via SMTP relay is to
+//! This is the most basic example of usage:
-//! do the following:
+//!
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
 //! use lettre::{Message, SmtpTransport, Transport};
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .body(String::from("Be happy!"))?;
 //!
 //! // Create TLS transport on port 465
 //! let sender = SmtpTransport::relay("smtp.example.com")?.build();
 //! // Send the email via remote relay
 //! let result = sender.send(&email);
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //! ```
 //!
 //! #### Authentication
 //!
 //! Example with authentication and connection pool:
 //!
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
 //! use lettre::{
-//!     message::header::ContentType,
+//!     transport::smtp::{
-//!     transport::smtp::authentication::{Credentials, Mechanism},
+//!         authentication::{Credentials, Mechanism},
 //!         PoolConfig,
 //!     },
 //!     Message, SmtpTransport, Transport,
 //! };
 //!
@@ -45,39 +71,35 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
-//! // Create the SMTPS transport
+//! // Create TLS transport on port 587 with STARTTLS
-//! let sender = SmtpTransport::relay("smtp.example.com")?
+//! let sender = SmtpTransport::starttls_relay("smtp.example.com")?
 //!     // Add credentials for authentication
 //!     .credentials(Credentials::new(
 //!         "username".to_owned(),
 //!         "password".to_owned(),
 //!     ))
-//!     // Optionally configure expected authentication mechanism
+//!     // Configure expected authentication mechanism
 //!     .authentication(vec![Mechanism::Plain])
 //!     // Connection pool settings
 //!     .pool_config(PoolConfig::new().max_size(20))
 //!     .build();
 //!
 //! // Send the email via remote relay
-//! sender.send(&email)?;
+//! let result = sender.send(&email);
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //! ```
 //!
-//! #### Shortening configuration
+//! You can specify custom TLS settings:
 //!
 //! It can be very repetitive to ask the user for every SMTP connection parameter.
 //! In some cases this can be simplified by using a connection URI instead.
 //!
 //! For more information take a look at [`SmtpTransport::from_url`] or [`AsyncSmtpTransport::from_url`].
 //!
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
 //! use lettre::{
-//!     message::header::ContentType,
+//!     transport::smtp::client::{Tls, TlsParameters},
 //!     transport::smtp::authentication::{Credentials, Mechanism},
 //!     Message, SmtpTransport, Transport,
 //! };
 //!
@@ -86,106 +108,25 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
-//! // Create the SMTPS transport
+//! // Custom TLS configuration
-//! let sender = SmtpTransport::from_url("smtps://username:password@smtp.example.com")?.build();
+//! let tls = TlsParameters::builder("smtp.example.com".to_owned())
-//!
+//!     .dangerous_accept_invalid_certs(true)
 //! // Send the email via remote relay
 //! sender.send(&email)?;
 //! # Ok(())
 //! # }
 //! ```
 //!
 //! #### Advanced configuration with custom TLS settings
 //!
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() -> Result<(), Box<dyn std::error::Error>> {
 //! use std::fs;
 //!
 //! use lettre::{
 //!     message::header::ContentType,
 //!     transport::smtp::client::{Certificate, Tls, TlsParameters},
 //!     Message, SmtpTransport, Transport,
 //! };
 //!
 //! let email = Message::builder()
 //!     .from("NoBody <nobody@domain.tld>".parse()?)
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! // Custom TLS configuration - Use a self signed certificate
 //! let cert = fs::read("self-signed.crt")?;
 //! let cert = Certificate::from_pem(&cert)?;
 //! let tls = TlsParameters::builder(/* TLS SNI value */ "smtp.example.com".to_owned())
 //!     .add_root_certificate(cert)
 //!     .build()?;
 //!
-//! // Create the SMTPS transport
+//! // Create TLS transport on port 465
 //! let sender = SmtpTransport::relay("smtp.example.com")?
-//!     .tls(Tls::Wrapper(tls))
+//!     // Custom TLS configuration
 //!     .tls(Tls::Required(tls))
 //!     .build();
 //!
 //! // Send the email via remote relay
-//! sender.send(&email)?;
+//! let result = sender.send(&email);
 //! assert!(result.is_ok());
 //! # Ok(())
 //! # }
 //! ```
 //!
 //! #### Connection pooling
 //!
 //! [`SmtpTransport`] and [`AsyncSmtpTransport`] store connections in
 //! a connection pool by default. This avoids connecting and disconnecting
 //! from the relay server for every message the application tries to send. For the connection pool
 //! to work the instance of the transport **must** be reused.
 //! In a webserver context it may go about this:
 //!
 //! ```rust,no_run
 //! # #[cfg(all(feature = "builder", any(feature = "native-tls", feature = "rustls-tls")))]
 //! # fn test() {
 //! use lettre::{
 //!     message::header::ContentType,
 //!     transport::smtp::{authentication::Credentials, PoolConfig},
 //!     Message, SmtpTransport, Transport,
 //! };
 //! #
 //! # type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
 //!
 //! /// The global application state
 //! #[derive(Debug)]
 //! struct AppState {
 //!     smtp: SmtpTransport,
 //!     // ... other global application parameters
 //! }
 //!
 //! impl AppState {
 //!     pub fn new(smtp_url: &str) -> Result<Self> {
 //!         let smtp = SmtpTransport::from_url(smtp_url)?.build();
 //!         Ok(Self { smtp })
 //!     }
 //! }
 //!
 //! fn handle_request(app_state: &AppState) -> Result<String> {
 //!     let email = Message::builder()
 //!         .from("NoBody <nobody@domain.tld>".parse()?)
 //!         .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!         .to("Hei <hei@domain.tld>".parse()?)
 //!         .subject("Happy new year")
 //!         .header(ContentType::TEXT_PLAIN)
 //!         .body(String::from("Be happy!"))?;
 //!
 //!     // Send the email via remote relay
 //!     app_state.smtp.send(&email)?;
 //!
 //!     Ok("The email has successfully been sent!".to_owned())
 //! }
 //! # }
 //! ```
 use std::time::Duration;
--- a/src/transport/smtp/pool/async_impl.rs
+++ b/src/transport/smtp/pool/async_impl.rs
@@ -78,7 +78,7 @@ impl<E: Executor> Pool<E> {
                            #[cfg(feature = "tracing")]
                            let mut created = 0;
-                            for _ in count..(min_idle as usize) {
+                            for _ in count..=(min_idle as usize) {
                                let conn = match pool.client.connection().await {
                                    Ok(conn) => conn,
                                    Err(err) => {
@@ -109,7 +109,7 @@ impl<E: Executor> Pool<E> {
                                #[cfg(feature = "tracing")]
                                tracing::debug!("dropped {} idle connections", dropped.len());
-                                abort_concurrent(dropped.into_iter().map(ParkedConnection::unpark))
+                                abort_concurrent(dropped.into_iter().map(|conn| conn.unpark()))
                                    .await;
                            }
                        }
@@ -229,7 +229,7 @@ impl<E: Executor> Drop for Pool<E> {
                handle.shutdown().await;
            }
-            abort_concurrent(connections.into_iter().map(ParkedConnection::unpark)).await;
+            abort_concurrent(connections.into_iter().map(|conn| conn.unpark())).await;
        });
    }
 }
--- a/src/transport/smtp/pool/sync_impl.rs
+++ b/src/transport/smtp/pool/sync_impl.rs
@@ -72,7 +72,7 @@ impl Pool {
                        #[cfg(feature = "tracing")]
                        let mut created = 0;
-                        for _ in count..(min_idle as usize) {
+                        for _ in count..=(min_idle as usize) {
                            let conn = match pool.client.connection() {
                                Ok(conn) => conn,
                                Err(err) => {
--- a/src/transport/smtp/transport.rs
+++ b/src/transport/smtp/transport.rs
@@ -11,31 +11,7 @@ use super::{ClientId, Credentials, Error, Mechanism, Response, SmtpConnection, S
 use super::{Tls, TlsParameters, SUBMISSIONS_PORT, SUBMISSION_PORT};
 use crate::{address::Envelope, Transport};
-/// Synchronously send emails using the SMTP protocol
+/// Sends emails using the SMTP protocol
 ///
 /// `SmtpTransport` is the primary way for communicating
 /// with SMTP relay servers to send email messages. It holds the
 /// client connect configuration and creates new connections
 /// as necessary.
 ///
 /// # Connection pool
 ///
 /// When the `pool` feature is enabled (default), `SmtpTransport` maintains a
 /// connection pool to manage SMTP connections. The pool:
 ///
 /// - Establishes a new connection when sending a message.
 /// - Recycles connections internally after a message is sent.
 /// - Reuses connections for subsequent messages, reducing connection setup overhead.
 ///
 /// The connection pool can grow to hold multiple SMTP connections if multiple
 /// emails are sent concurrently, as SMTP does not support multiplexing within a
 /// single connection.
 ///
 /// However, **connection reuse is not possible** if the `SmtpTransport` instance
 /// is dropped after every email send operation. You must reuse the instance
 /// of this struct for the connection pool to be of any use.
 ///
 /// To customize connection pool settings, use [`SmtpTransportBuilder::pool_config`].
 #[cfg_attr(docsrs, doc(cfg(feature = "smtp-transport")))]
 #[derive(Clone)]
 pub struct SmtpTransport {
@@ -56,7 +32,7 @@ impl Transport for SmtpTransport {
        let result = conn.send(envelope, email)?;
        #[cfg(not(feature = "pool"))]
-        conn.abort();
+        conn.quit()?;
        Ok(result)
    }
@@ -139,72 +115,54 @@ impl SmtpTransport {
    /// Creates a `SmtpTransportBuilder` from a connection URL
    ///
-    /// The protocol, credentials, host, port and EHLO name can be provided
+    /// The protocol, credentials, host and port can be provided in a single URL.
-    /// in a single URL. This may be simpler than having to configure SMTP
+    /// Use the scheme `smtp` for an unencrypted relay (optionally in combination with the
-    /// through multiple configuration parameters and then having to pass
+    /// `tls` parameter to allow/require STARTTLS) or `smtps` for SMTP over TLS.
-    /// those options to lettre.
+    /// The path section of the url can be used to set an alternative name for
    /// the HELO / EHLO command.
    /// For example `smtps://username:password@smtp.example.com/client.example.com:465`
    /// will set the HELO / EHLO name `client.example.com`.
    ///
-    /// The URL is created in the following way:
+    /// <table>
-    /// `scheme://user:pass@hostname:port/ehlo-name?tls=TLS`.
+    ///   <thead>
-    ///
+    ///     <tr>
-    /// `user` (Username) and `pass` (Password) are optional in case the
+    ///       <th>scheme</th>
-    /// SMTP relay doesn't require authentication. When `port` is not
+    ///       <th>tls parameter</th>
-    /// configured it is automatically determined based on the `scheme`.
+    ///       <th>example</th>
-    /// `ehlo-name` optionally overwrites the hostname sent for the EHLO
+    ///       <th>remarks</th>
-    /// command. `TLS` controls whether STARTTLS is simply enabled
+    ///     </tr>
-    /// (`opportunistic` - not enough to prevent man-in-the-middle attacks)
+    ///   </thead>
-    /// or `required` (require the server to upgrade the connection to
+    ///   <tbody>
-    /// STARTTLS, otherwise fail on suspicion of main-in-the-middle attempt).
+    ///     <tr>
-    ///
+    ///      <td>smtps</td>
-    /// Use the following table to construct your SMTP url:
+    ///      <td>-</td>
-    ///
+    ///      <td>smtps://smtp.example.com</td>
-    /// | scheme  | `tls` query parameter | example                                            | default port | remarks                                                                                                                               |
+    ///      <td>SMTP over TLS, recommended method</td>
-    /// | ------- | --------------------- | -------------------------------------------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------- |
+    ///     </tr>
-    /// | `smtps` | unset                 | `smtps://user:pass@hostname:port`                  | 465          | SMTP over TLS, recommended method                                                                                                     |
+    ///     <tr>
-    /// | `smtp`  | `required`            | `smtp://user:pass@hostname:port?tls=required`      | 587          | SMTP with STARTTLS required, when SMTP over TLS is not available                                                                      |
+    ///      <td>smtp</td>
-    /// | `smtp`  | `opportunistic`       | `smtp://user:pass@hostname:port?tls=opportunistic` | 587          | SMTP with optionally STARTTLS when supported by the server. Not suitable for production use: vulnerable to a man-in-the-middle attack |
+    ///      <td>required</td>
-    /// | `smtp`  | unset                 | `smtp://user:pass@hostname:port`                   | 587          | Always unencrypted SMTP. Not suitable for production use: sends all data unencrypted                                                  |
+    ///      <td>smtp://smtp.example.com?tls=required</td>
-    ///
+    ///      <td>SMTP with STARTTLS required, when SMTP over TLS is not available</td>
-    /// IMPORTANT: some parameters like `user` and `pass` cannot simply
+    ///     </tr>
-    /// be concatenated to construct the final URL because special characters
+    ///     <tr>
-    /// contained within the parameter may confuse the URL decoder.
+    ///      <td>smtp</td>
-    /// Manually URL encode the parameters before concatenating them or use
+    ///      <td>opportunistic</td>
-    /// a proper URL encoder, like the following cargo script:
+    ///      <td>smtp://smtp.example.com?tls=opportunistic</td>
-    ///
+    ///      <td>
-    /// ```rust
+    ///         SMTP with optionally STARTTLS when supported by the server.
-    /// # let _ = r#"
+    ///         Caution: this method is vulnerable to a man-in-the-middle attack.
-    /// #!/usr/bin/env cargo
+    ///         Not recommended for production use.
-    ///
+    ///       </td>
-    /// //! ```cargo
+    ///     </tr>
-    /// //! [dependencies]
+    ///     <tr>
-    /// //! url = "2"
+    ///      <td>smtp</td>
-    /// //! ```
+    ///      <td>-</td>
-    /// # "#;
+    ///      <td>smtp://smtp.example.com</td>
-    ///
+    ///      <td>Unencrypted SMTP, not recommended for production use.</td>
-    /// use url::Url;
+    ///     </tr>
-    ///
+    ///   </tbody>
-    /// fn main() {
+    /// </table>
    ///     // don't touch this line
    ///     let mut url = Url::parse("foo://bar").unwrap();
    ///
    ///     // configure the scheme (`smtp` or `smtps`) here.
    ///     url.set_scheme("smtps").unwrap();
    ///     // configure the username and password.
    ///     // remove the following two lines if unauthenticated.
    ///     url.set_username("username").unwrap();
    ///     url.set_password(Some("password")).unwrap();
    ///     // configure the hostname
    ///     url.set_host(Some("smtp.example.com")).unwrap();
    ///     // configure the port - only necessary if using a non-default port
    ///     url.set_port(Some(465)).unwrap();
    ///     // configure the EHLO name
    ///     url.set_path("ehlo-name");
    ///
    ///     println!("{url}");
    /// }
    /// ```
    ///
    /// The connection URL can then be used in the following way:
    ///
    /// ```rust,no_run
    /// use lettre::{
@@ -212,7 +170,6 @@ impl SmtpTransport {
    ///     SmtpTransport, Transport,
    /// };
    ///
    /// # fn main() -> Result<(), Box<dyn std::error::Error>> {
    /// let email = Message::builder()
    ///     .from("NoBody <nobody@domain.tld>".parse().unwrap())
    ///     .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
@@ -223,12 +180,15 @@ impl SmtpTransport {
    ///     .unwrap();
    ///
    /// // Open a remote connection to example
-    /// let mailer = SmtpTransport::from_url("smtps://username:password@smtp.example.com")?.build();
+    /// let mailer = SmtpTransport::from_url("smtps://username:password@smtp.example.com:465")
    ///     .unwrap()
    ///     .build();
    ///
    /// // Send the email
-    /// mailer.send(&email)?;
+    /// match mailer.send(&email) {
-    /// # Ok(())
+    ///     Ok(_) => println!("Email sent successfully!"),
-    /// # }
+    ///     Err(e) => panic!("Could not send email: {e:?}"),
    /// }
    /// ```
    #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
    #[cfg_attr(
@@ -286,7 +246,7 @@ impl SmtpTransportBuilder {
        self
    }
-    /// Set the authentication credentials to use
+    /// Set the authentication mechanism to use
    pub fn credentials(mut self, credentials: Credentials) -> Self {
        self.info.credentials = Some(credentials);
        self
@@ -305,34 +265,12 @@ impl SmtpTransportBuilder {
    }
    /// Set the port to use
    ///
    /// # ⚠️⚠️⚠️ You probably don't need to call this method ⚠️⚠️⚠️
    ///
    /// lettre usually picks the correct `port` when building
    /// [`SmtpTransport`] using [`SmtpTransport::relay`] or
    /// [`SmtpTransport::starttls_relay`].
    ///
    /// # Errors
    ///
    /// Using the incorrect `port` and [`Self::tls`] combination may
    /// lead to hard to debug IO errors coming from the TLS library.
    pub fn port(mut self, port: u16) -> Self {
        self.info.port = port;
        self
    }
    /// Set the TLS settings to use
    ///
    /// # ⚠️⚠️⚠️ You probably don't need to call this method ⚠️⚠️⚠️
    ///
    /// By default lettre chooses the correct `tls` configuration when
    /// building [`SmtpTransport`] using [`SmtpTransport::relay`] or
    /// [`SmtpTransport::starttls_relay`].
    ///
    /// # Errors
    ///
    /// Using the wrong [`Tls`] and [`Self::port`] combination may
    /// lead to hard to debug IO errors coming from the TLS library.
    #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
    #[cfg_attr(
        docsrs,
@@ -398,11 +336,11 @@ impl SmtpClient {
        match &self.info.tls {
            Tls::Opportunistic(tls_parameters) => {
                if conn.can_starttls() {
-                    conn.starttls(tls_parameters, &self.info.hello_name)?;
+                    conn = conn.starttls(tls_parameters, &self.info.hello_name)?;
                }
            }
            Tls::Required(tls_parameters) => {
-                conn.starttls(tls_parameters, &self.info.hello_name)?;
+                conn = conn.starttls(tls_parameters, &self.info.hello_name)?;
            }
            _ => (),
        }
--- a/src/transport/smtp/util.rs
+++ b/src/transport/smtp/util.rs
@@ -6,7 +6,7 @@ use std::fmt::{Display, Formatter, Result as FmtResult};
 #[derive(Debug)]
 pub struct XText<'a>(pub &'a str);
-impl Display for XText<'_> {
+impl<'a> Display for XText<'a> {
    fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
        let mut rest = self.0;
        while let Some(idx) = rest.find(|c| c < '!' || c == '+' || c == '=') {
@@ -38,7 +38,9 @@ mod tests {
            ("bjørn", "bjørn"),
            ("Ø+= ❤️‰", "Ø+2B+3D+20❤️‰"),
            ("+", "+2B"),
-        ] {
+        ]
        .iter()
        {
            assert_eq!(format!("{}", XText(input)), (*expect).to_owned());
        }
    }
--- a/src/transport/stub/mod.rs
+++ b/src/transport/stub/mod.rs
@@ -11,9 +11,7 @@
 //! ```rust
 //! # #[cfg(feature = "builder")]
 //! # {
-//! use lettre::{
+//! use lettre::{transport::stub::StubTransport, Message, Transport};
 //!     message::header::ContentType, transport::stub::StubTransport, Message, Transport,
 //! };
 //!
 //! # use std::error::Error;
 //! # fn try_main() -> Result<(), Box<dyn Error>> {
@@ -22,11 +20,11 @@
 //!     .reply_to("Yuin <yuin@domain.tld>".parse()?)
 //!     .to("Hei <hei@domain.tld>".parse()?)
 //!     .subject("Happy new year")
 //!     .header(ContentType::TEXT_PLAIN)
 //!     .body(String::from("Be happy!"))?;
 //!
 //! let mut sender = StubTransport::new_ok();
-//! sender.send(&email)?;
+//! let result = sender.send(&email);
 //! assert!(result.is_ok());
 //! assert_eq!(
 //!     sender.messages(),
 //!     vec![(
Author	SHA1	Message	Date
Paolo Barbolini	efee4b5d72	Fix warnings	2024-03-19 16:21:10 +01:00
Paolo Barbolini	57d7bf25cc	Replace try_smtp macro with more resilient method	2024-03-19 16:21:10 +01:00
Paolo Barbolini	c52c596458	Drop ref syntax	2024-03-10 15:28:54 +01:00
Paolo Barbolini	53dee3e31f	Drop need for NetworkStream::None variant	2024-03-10 15:28:54 +01:00