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
28 changed files with 1081 additions and 1569 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
@@ -80,7 +80,7 @@ jobs:

    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
@@ -1,97 +1,3 @@
-<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)

--- 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 = "0.11.9"
+version = "0.11.4"
 description = "Email client"
 readme = "README.md"
 homepage = "https://lettre.rs"
@@ -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 = "0.2.5", 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-pki-types = { version = "1.7", optional = true }
+rustls-native-certs = { version = "0.7", 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) 2019-2024 Paolo Barbolini <paolo@paolo565.org>
+Copyright (c) 2014-2022 Alexis Mousset <contact@amousset.me>
+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/0.11.9">
-    <img src="https://deps.rs/crate/lettre/0.11.9/status.svg"
+  <a href="https://deps.rs/crate/lettre/0.11.4">
+    <img src="https://deps.rs/crate/lettre/0.11.4/status.svg"
      alt="dependency status" />
  </a>
 </div>
@@ -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()
-        .from("NoBody <nobody@domain.tld>".parse().unwrap())
-        .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 email = Message::builder()
+    .from("NoBody <nobody@domain.tld>".parse().unwrap())
+    .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 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
-    let mailer = SmtpTransport::relay("smtp.gmail.com")
-        .unwrap()
-        .credentials(creds)
-        .build();
+// Open a remote connection to gmail
+let mailer = SmtpTransport::relay("smtp.gmail.com")
+    .unwrap()
+    .credentials(creds)
+    .build();

-    // Send the email
-    match mailer.send(&email) {
-        Ok(_) => println!("Email sent successfully!"),
-        Err(e) => panic!("Could not send email: {e:?}"),
-    }
+// Send the email
+match mailer.send(&email) {
+    Ok(_) => println!("Email sent successfully!"),
+    Err(e) => panic!("Could not send email: {e:?}"),
 }
 ```

--- 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/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
@@ -109,7 +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/0.11.9")]
+#![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)]
@@ -174,7 +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/body.rs
+++ b/src/message/body.rs
@@ -1,11 +1,11 @@
-use std::{mem, ops::Deref, sync::Arc};
+use std::{mem, ops::Deref};

 use crate::message::header::ContentTransferEncoding;

 /// A [`Message`][super::Message] or [`SinglePart`][super::SinglePart] body that has already been encoded.
 #[derive(Debug, Clone)]
 pub struct Body {
-    buf: Arc<[u8]>,
+    buf: Vec<u8>,
    encoding: ContentTransferEncoding,
 }

@@ -39,7 +39,7 @@ impl Body {

        let encoding = buf.encoding(false);
        buf.encode_crlf();
-        Self::new_impl(Vec::from(buf).into(), encoding)
+        Self::new_impl(buf.into(), encoding)
    }

    /// Encode the supplied `buf`, using the provided `encoding`.
@@ -77,7 +77,7 @@ impl Body {
        }

        buf.encode_crlf();
-        Ok(Self::new_impl(Vec::from(buf).into(), encoding))
+        Ok(Self::new_impl(buf.into(), encoding))
    }

    /// Builds a new `Body` using a pre-encoded buffer.
@@ -87,14 +87,11 @@ impl Body {
    /// `buf` shouldn't contain non-ascii characters, lines longer than 1000 characters or nul bytes.
    #[inline]
    pub fn dangerous_pre_encoded(buf: Vec<u8>, encoding: ContentTransferEncoding) -> Self {
-        Self {
-            buf: buf.into(),
-            encoding,
-        }
+        Self { buf, encoding }
    }

    /// Encodes the supplied `buf` using the provided `encoding`
-    fn new_impl(buf: Arc<[u8]>, encoding: ContentTransferEncoding) -> Self {
+    fn new_impl(buf: Vec<u8>, encoding: ContentTransferEncoding) -> Self {
        match encoding {
            ContentTransferEncoding::SevenBit
            | ContentTransferEncoding::EightBit
@@ -136,16 +133,7 @@ impl Body {

    /// Consumes `Body` and returns the inner `Vec<u8>`
    #[inline]
-    #[deprecated(
-        note = "The inner memory is not stored into `Vec<u8>` anymore. Consider using `into_inner`"
-    )]
    pub fn into_vec(self) -> Vec<u8> {
-        self.buf.to_vec()
-    }
-
-    /// Consumes `Body` and returns the inner `Arc<[u8]>`
-    #[inline]
-    pub fn into_inner(self) -> Arc<[u8]> {
        self.buf
    }
 }
--- 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/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");
                }

--- 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::*,
@@ -18,7 +18,6 @@ pub use self::{
    special::*,
    textual::*,
 };
-use super::EmailFormat;
 use crate::BoxError;

 mod content;
@@ -125,18 +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)
    }
 }
@@ -155,25 +158,21 @@ impl Display for Headers {
    }
 }

-impl EmailFormat for Headers {
-    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
-        for value in &self.headers {
-            out.extend([
-                Cow::Borrowed(value.name.as_bytes()),
-                Cow::Borrowed(b": "),
-                Cow::Borrowed(value.encoded_value.as_bytes()),
-                Cow::Borrowed(b"\r\n"),
-            ]);
-        }
-    }
-}
-
 /// A possible error when converting a `HeaderName` from another type.
 // comes from `http` crate
 #[allow(missing_copy_implementations)]
-#[derive(Debug, Clone)]
-#[non_exhaustive]
-pub struct InvalidHeaderName;
+#[derive(Clone)]
+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 {
@@ -190,11 +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: () })
        }
    }

@@ -255,19 +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
    }
 }

@@ -342,7 +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,
@@ -461,60 +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]
@@ -660,14 +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?w6FuIMOTIFJ1ZGHDrQ==?= <sean@example.com>\r\n",
+                "  =?utf-8?b?SsSBbmlzIELEk3J6acWGxaE=?= <janis@example.com>,\r\n",
+                "  =?utf-8?b?U2XDoW4gw5MgUnVkYcOt?= <sean@example.com>\r\n",
            )
        );
    }
@@ -732,6 +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!(
@@ -741,8 +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?w6FuIMOTIFJ1ZGHDrQ==?= <sean@example.com>\r\n",
+                "  =?utf-8?b?SsSBbmlzIELEk3J6acWGxaE=?= <janis@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))))
-        .padded()
-        .then_ignore(end())
+    choice((name_addr(), addr_spec().map(|addr| (None, addr)))).then_ignore(end())
 }

 // name-addr       =       [display-name] angle-addr
--- 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('<')?;
        }

@@ -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)?;
@@ -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;
@@ -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
@@ -1,4 +1,4 @@
-use std::{borrow::Cow, iter::repeat_with, sync::Arc};
+use std::{io::Write, iter::repeat_with};

 use mime::Mime;

@@ -28,7 +28,7 @@ impl Part {
 }

 impl EmailFormat for Part {
-    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
+    fn format(&self, out: &mut Vec<u8>) {
        match self {
            Part::Single(part) => part.format(out),
            Part::Multi(part) => part.format(out),
@@ -71,7 +71,7 @@ impl SinglePartBuilder {

        SinglePart {
            headers: self.headers,
-            body: body.into_inner(),
+            body: body.into_vec(),
        }
    }
 }
@@ -100,7 +100,7 @@ impl Default for SinglePartBuilder {
 #[derive(Debug, Clone)]
 pub struct SinglePart {
    headers: Headers,
-    body: Arc<[u8]>,
+    body: Vec<u8>,
 }

 impl SinglePart {
@@ -138,18 +138,24 @@ impl SinglePart {

    /// Get message content formatted for sending
    pub fn formatted(&self) -> Vec<u8> {
-        self.format_to_vec()
+        let mut out = Vec::new();
+        self.format(&mut out);
+        out
+    }
+
+    /// Format only the signlepart body
+    fn format_body(&self, out: &mut Vec<u8>) {
+        out.extend_from_slice(&self.body);
+        out.extend_from_slice(b"\r\n");
    }
 }

 impl EmailFormat for SinglePart {
-    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
-        self.headers.format(out);
-        out.extend([
-            Cow::Borrowed("\r\n".as_bytes()),
-            Cow::Borrowed(&self.body),
-            Cow::Borrowed(b"\r\n"),
-        ]);
+    fn format(&self, out: &mut Vec<u8>) {
+        write!(out, "{}", self.headers)
+            .expect("A Write implementation panicked while formatting headers");
+        out.extend_from_slice(b"\r\n");
+        self.format_body(out);
    }
 }

@@ -378,36 +384,33 @@ impl MultiPart {

    /// Get message content formatted for SMTP
    pub fn formatted(&self) -> Vec<u8> {
-        self.format_to_vec()
+        let mut out = Vec::new();
+        self.format(&mut out);
+        out
    }

    /// Format only the multipart body
-    fn format_body<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
+    fn format_body(&self, out: &mut Vec<u8>) {
        let boundary = self.boundary();

        for part in &self.parts {
-            out.extend([
-                Cow::Borrowed("--".as_bytes()),
-                // FIXME: this clone shouldn't exist
-                Cow::Owned(boundary.clone().into()),
-                Cow::Borrowed("\r\n".as_bytes()),
-            ]);
+            out.extend_from_slice(b"--");
+            out.extend_from_slice(boundary.as_bytes());
+            out.extend_from_slice(b"\r\n");
            part.format(out);
        }

-        out.extend([
-            Cow::Borrowed("--".as_bytes()),
-            Cow::Owned(boundary.into()),
-            Cow::Borrowed("--\r\n".as_bytes()),
-        ]);
+        out.extend_from_slice(b"--");
+        out.extend_from_slice(boundary.as_bytes());
+        out.extend_from_slice(b"--\r\n");
    }
 }

 impl EmailFormat for MultiPart {
-    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
-        self.headers.format(out);
-        out.extend([Cow::Borrowed("\r\n".as_bytes())]);
-
+    fn format(&self, out: &mut Vec<u8>) {
+        write!(out, "{}", self.headers)
+            .expect("A Write implementation panicked while formatting headers");
+        out.extend_from_slice(b"\r\n");
        self.format_body(out);
    }
 }
@@ -417,6 +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
@@ -198,7 +198,7 @@
 //! ```
 //! </details>

-use std::{borrow::Cow, iter, sync::Arc, time::SystemTime};
+use std::{io::Write, iter, time::SystemTime};

 pub use attachment::Attachment;
 pub use body::{Body, IntoBody, MaybeString};
@@ -226,23 +226,7 @@ const DEFAULT_MESSAGE_ID_DOMAIN: &str = "localhost";
 /// Something that can be formatted as an email message
 trait EmailFormat {
    // Use a writer?
-    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>);
-
-    fn format_to_vec(&self) -> Vec<u8> {
-        struct Formatter(Vec<u8>);
-
-        impl<'a> Extend<Cow<'a, [u8]>> for Formatter {
-            fn extend<T: IntoIterator<Item = Cow<'a, [u8]>>>(&mut self, iter: T) {
-                for chunk in iter {
-                    self.0.extend_from_slice(&chunk);
-                }
-            }
-        }
-
-        let mut formatted = Formatter(Vec::new());
-        self.format(&mut formatted);
-        formatted.0
-    }
+    fn format(&self, out: &mut Vec<u8>);
 }

 /// A builder for messages
@@ -470,7 +454,7 @@ impl MessageBuilder {
        let body = body.into_body(maybe_encoding);

        self.headers.set(body.encoding());
-        self.build(MessageBody::Raw(body.into_inner()))
+        self.build(MessageBody::Raw(body.into_vec()))
    }

    /// Create message using mime body ([`MultiPart`][self::MultiPart])
@@ -505,7 +489,7 @@ pub struct Message {
 #[derive(Clone, Debug)]
 enum MessageBody {
    Mime(Part),
-    Raw(Arc<[u8]>),
+    Raw(Vec<u8>),
 }

 impl Message {
@@ -531,7 +515,9 @@ impl Message {

    /// Get message content formatted for SMTP
    pub fn formatted(&self) -> Vec<u8> {
-        self.format_to_vec()
+        let mut out = Vec::new();
+        self.format(&mut out);
+        out
    }

    #[cfg(feature = "dkim")]
@@ -607,13 +593,15 @@ impl Message {
 }

 impl EmailFormat for Message {
-    fn format<'a>(&'a self, out: &mut impl Extend<Cow<'a, [u8]>>) {
-        self.headers.format(out);
+    fn format(&self, out: &mut Vec<u8>) {
+        write!(out, "{}", self.headers)
+            .expect("A Write implementation panicked while formatting headers");

        match &self.body {
            MessageBody::Mime(p) => p.format(out),
            MessageBody::Raw(r) => {
-                out.extend([Cow::Borrowed("\r\n".as_bytes()), Cow::Borrowed(r)]);
+                out.extend_from_slice(b"\r\n");
+                out.extend_from_slice(r)
            }
        }
    }
--- 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:
--- a/src/transport/smtp/async_transport.rs
+++ b/src/transport/smtp/async_transport.rs
@@ -82,6 +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(
@@ -116,6 +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(
@@ -351,6 +353,7 @@ impl AsyncSmtpTransportBuilder {
    #[cfg(any(
        feature = "tokio1-native-tls",
        feature = "tokio1-rustls-tls",
+        feature = "async-std1-native-tls",
        feature = "async-std1-rustls-tls"
    ))]
    #[cfg_attr(
--- 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,
 }
@@ -126,7 +112,6 @@ impl AsyncSmtpConnection {
        let stream = BufReader::new(stream);
        let mut conn = AsyncSmtpConnection {
            stream,
-            panic: false,
            server_info: ServerInfo::default(),
        };
        // TODO log
@@ -170,30 +155,26 @@ impl AsyncSmtpConnection {
            mail_options.push(MailParameter::Body(MailBodyParameter::EightBitMime));
        }

-        try_smtp!(
-            self.command(Mail::new(envelope.from().cloned(), mail_options))
-                .await,
-            self
-        );
+        self.command(Mail::new(envelope.from().cloned(), mail_options))
+            .await?;

        // Recipient
        for to_address in envelope.to() {
-            try_smtp!(
-                self.command(Rcpt::new(to_address.clone(), vec![])).await,
-                self
-            );
+            self.command(Rcpt::new(to_address.clone(), vec![])).await?;
        }

        // Data
-        try_smtp!(self.command(Data).await, self);
+        self.command(Data).await?;

        // Message content
-        let result = try_smtp!(self.message(email).await, self);
-        Ok(result)
+        self.message(email).await
    }

    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 {
@@ -208,18 +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.stream.get_mut().upgrade_tls(tls_parameters).await?;
+            self.command(Starttls).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);
-            Ok(())
+            self.ehlo(hello_name).await?;
+            Ok(self)
        } else {
            Err(error::client("STARTTLS is not supported on this server"))
        }
@@ -227,22 +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);
-        self.server_info = try_smtp!(ServerInfo::from_response(&ehlo_response), self);
+        let ehlo_response = self.command(Ehlo::new(hello_name.clone())).await?;
+        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
-        if !self.panic {
-            self.panic = true;
-            let _ = self.command(Quit).await;
+        match self.stream.get_ref().state() {
+            ConnectionState::Ok | ConnectionState::Broken => {
+                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
@@ -279,15 +264,13 @@ impl AsyncSmtpConnection {

        while challenges > 0 && response.has_code(334) {
            challenges -= 1;
-            response = try_smtp!(
-                self.command(Auth::new_from_response(
+            response = self
+                .command(Auth::new_from_response(
                    mechanism,
                    credentials.clone(),
                    &response,
                )?)
-                .await,
-                self
-            );
+                .await?;
        }

        if challenges == 0 {
@@ -315,6 +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)
@@ -326,6 +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(())
@@ -333,6 +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
@@ -346,6 +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 {
@@ -353,7 +346,7 @@ impl AsyncSmtpConnection {
                            response.code(),
                            Some(response.message().collect()),
                        ))
-                    }
+                    };
                }
                Err(nom::Err::Failure(e)) => {
                    return Err(error::response(e.to_string()));
@@ -373,10 +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,
-    Result as IoResult,
+    AsyncRead as FuturesAsyncRead, AsyncWrite as FuturesAsyncWrite, 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 {
-            debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
+        AsyncNetworkStream {
+            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",
-                ))
-            }
        }
    }

@@ -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)
    }
@@ -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> {
-        match &self.inner {
+    pub async fn upgrade_tls(self, tls_parameters: TlsParameters) -> Result<Self, Error> {
+        match self.inner {
            #[cfg(all(
                feature = "tokio1",
                not(any(
@@ -267,40 +273,35 @@ impl AsyncNetworkStream {
                feature = "tokio1-rustls-tls",
                feature = "tokio1-boring-tls"
            ))]
-            InnerAsyncNetworkStream::Tokio1Tcp(_) => {
-                // get owned TcpStream
-                let tcp_stream = mem::replace(&mut self.inner, InnerAsyncNetworkStream::None);
-                let tcp_stream = match tcp_stream {
-                    InnerAsyncNetworkStream::Tokio1Tcp(tcp_stream) => tcp_stream,
-                    _ => unreachable!(),
-                };
-
-                self.inner = Self::upgrade_tokio1_tls(tcp_stream, tls_parameters)
+            InnerAsyncNetworkStream::Tokio1Tcp(tcp_stream) => {
+                let 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")]
-            InnerAsyncNetworkStream::AsyncStd1Tcp(_) => {
-                // get owned TcpStream
-                let tcp_stream = mem::replace(&mut self.inner, InnerAsyncNetworkStream::None);
-                let tcp_stream = match tcp_stream {
-                    InnerAsyncNetworkStream::AsyncStd1Tcp(tcp_stream) => tcp_stream,
-                    _ => unreachable!(),
-                };
-
-                self.inner = Self::upgrade_asyncstd1_tls(tcp_stream, tls_parameters)
+            #[cfg(any(feature = "async-std1-native-tls", feature = "async-std1-rustls-tls"))]
+            InnerAsyncNetworkStream::AsyncStd1Tcp(tcp_stream) => {
+                let inner = Self::upgrade_asyncstd1_tls(tcp_stream, tls_parameters)
                    .await
                    .map_err(error::connection)?;
-                Ok(())
+                Ok(Self {
+                    inner,
+                    state: ConnectionState::Ok,
+                })
            }
-            _ => Ok(()),
+            _ => Ok(self),
        }
    }

@@ -374,7 +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,
@@ -385,6 +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) => {
@@ -425,51 +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"),
        }
    }

@@ -507,6 +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()
@@ -516,7 +498,6 @@ impl AsyncNetworkStream {
                .first()
                .unwrap()
                .to_vec()),
-            InnerAsyncNetworkStream::None => panic!("InnerNetworkStream::None must never be built"),
        }
    }
 }
@@ -566,12 +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))
-            }
        }
    }
 }
@@ -593,12 +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))
-            }
        }
    }

@@ -614,16 +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),
@@ -635,12 +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
-        );
+        self.command(Mail::new(envelope.from().cloned(), mail_options))?;

        // 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);
-        Ok(result)
+        self.message(email)
    }

    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.stream.get_mut().upgrade_tls(tls_parameters)?;
+                self.command(Starttls)?;
+                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);
-                Ok(())
+                self.ehlo(hello_name)?;
+                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);
-        self.server_info = try_smtp!(ServerInfo::from_response(&ehlo_response), self);
+        let ehlo_response = self.command(Ehlo::new(hello_name.clone()))?;
+        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
-        if !self.panic {
-            self.panic = true;
-            let _ = self.command(Quit);
+        match self.stream.get_ref().state() {
+            ConnectionState::Ok | ConnectionState::Broken => {
+                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!(
-                self.command(Auth::new_from_response(
-                    mechanism,
-                    credentials.clone(),
-                    &response,
-                )?),
-                self
-            );
+            response = self.command(Auth::new_from_response(
+                mechanism,
+                credentials.clone(),
+                &response,
+            )?)?;
        }

        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, Ipv4Addr, Shutdown, SocketAddr, SocketAddrV4, TcpStream, ToSocketAddrs},
+    net::{IpAddr, Shutdown, SocketAddr, 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 {
-            debug_assert!(false, "InnerNetworkStream::None must never be built");
+        NetworkStream {
+            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(())
-            }
        }
    }

@@ -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> {
-        match &self.inner {
+    pub fn upgrade_tls(self, tls_parameters: &TlsParameters) -> Result<Self, Error> {
+        match self.inner {
            #[cfg(not(any(
                feature = "native-tls",
                feature = "rustls-tls",
@@ -157,18 +153,14 @@ impl NetworkStream {
            }

            #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
-            InnerNetworkStream::Tcp(_) => {
-                // get owned TcpStream
-                let tcp_stream = mem::replace(&mut self.inner, InnerNetworkStream::None);
-                let tcp_stream = match tcp_stream {
-                    InnerNetworkStream::Tcp(tcp_stream) => tcp_stream,
-                    _ => unreachable!(),
-                };
-
-                self.inner = Self::upgrade_tls_impl(tcp_stream, tls_parameters)?;
-                Ok(())
+            InnerNetworkStream::Tcp(tcp_stream) => {
+                let inner = Self::upgrade_tls_impl(tcp_stream, tls_parameters)?;
+                Ok(Self {
+                    inner,
+                    state: ConnectionState::Ok,
+                })
            }
-            _ => Ok(()),
+            _ => Ok(self),
        }
    }

@@ -216,36 +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"),
        }
    }

@@ -275,7 +237,6 @@ impl NetworkStream {
                .unwrap()
                .to_der()
                .map_err(error::tls)?),
-            InnerNetworkStream::None => panic!("InnerNetworkStream::None must never be built"),
        }
    }

@@ -288,10 +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(())
-            }
        }
    }

@@ -306,10 +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(())
-            }
        }
    }
 }
@@ -324,10 +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)
-            }
        }
    }
 }
@@ -342,10 +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)
-            }
        }
    }

@@ -358,10 +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(())
-            }
        }
    }
 }
--- 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},
-    server::ParsedCertificate,
+    pki_types::{CertificateDer, ServerName, UnixTime},
    ClientConfig, DigitallySignedStruct, Error as TlsError, RootCertStore, SignatureScheme,
 };

@@ -111,7 +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.
@@ -142,7 +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"))]
@@ -156,7 +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"))]
@@ -172,20 +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`.
@@ -197,11 +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(
-        docsrs,
-        doc(cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls")))
-    )]
+    ///
+    /// Hostname verification can only be disabled with the `native-tls` TLS backend.
+    #[cfg(any(feature = "native-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
@@ -289,10 +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),
@@ -335,15 +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,
@@ -379,73 +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 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) -> Result<(), Error> {
-            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"
-            );
-            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)?;
-            }
-        }
-
-        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,
-            };
+        let tls = if self.accept_invalid_certs {
            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 = 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()
-        };
+        let tls = tls.with_no_client_auth();

        Ok(TlsParameters {
            connector: InnerTlsParameters::RustlsTls(Arc::new(tls)),
@@ -510,7 +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 {
@@ -577,109 +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],
-        key: &[u8],
-    ) -> Result<(Vec<CertificateDer<'static>>, PrivateKeyDer<'static>), Error> {
-        let mut key = key;
-        let key = rustls_pemfile::private_key(&mut key).unwrap().unwrap();
-        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 {
-    ignore_invalid_hostnames: bool,
-    ignore_invalid_certs: bool,
-    roots: RootCertStore,
-    signature_algorithms: WebPkiSupportedAlgorithms,
-}
+struct InvalidCertsVerifier;

 #[cfg(feature = "rustls-tls")]
 impl ServerCertVerifier for InvalidCertsVerifier {
    fn verify_server_cert(
        &self,
-        end_entity: &CertificateDer<'_>,
-        intermediates: &[CertificateDer<'_>],
-        server_name: &ServerName<'_>,
+        _end_entity: &CertificateDer<'_>,
+        _intermediates: &[CertificateDer<'_>],
+        _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/extension.rs
+++ b/src/transport/smtp/extension.rs
@@ -291,8 +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/transport.rs
+++ b/src/transport/smtp/transport.rs
@@ -336,11 +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)?;
            }
            _ => (),
        }
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