fix

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.44.1 to 1.44.2.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](https://github.com/tokio-rs/tokio/compare/tokio-1.44.1...tokio-1.44.2)

---
updated-dependencies:
- dependency-name: tokio
  dependency-version: 1.44.2
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -1,3 +1,57 @@
+<a name="v0.11.17"></a>
+### v0.11.17 (2025-06-06)
+
+#### Features
+
+* Add support for `rustls-platform-verifier` ([#1081])
+
+#### Misc
+
+* Change readme example to use `Mailbox::new` instead of string parsing ([#1090])
+* Replace futures-util `Mutex` with std `Mutex` in `AsyncStubTransport` ([#1091])
+* Avoid duplicate `abort_concurrent` implementation ([#1092])
+
+[#1081]: https://github.com/lettre/lettre/pull/1081
+[#1090]: https://github.com/lettre/lettre/pull/1090
+[#1091]: https://github.com/lettre/lettre/pull/1091
+[#1092]: https://github.com/lettre/lettre/pull/1092
+
+<a name="v0.11.16"></a>
+### v0.11.16 (2025-05-12)
+
+#### Features
+
+* Always implement `Clone` for `AsyncFileTransport` ([#1075])
+
+#### Changes
+
+* `Tls`, `CertificateStore`, `TlsParameters`, `TlsParametersBuilder`, `Certificate` and `Identity`
+  are now marked as deprecated when no TLS backend is enabled. They will be properly feature gated
+  in lettre v0.12 ([#1084])
+
+#### Misc
+
+* Gate `web-time` behind `cfg(target_arch = "wasm32")]` ([#1086])
+* Add missing `#[doc(cfg(...))]` attributes ([#1086])
+* Upgrade `webpki-roots` to v1 ([#1088])
+* Cleanup internal `TlsParameters` and `(Async)NetworkStream` structures ([#1082])
+* Feature gate internal `TransportBuilder::tls` to avoid recursive call site warnings ([#1083])
+* Fix workaround for embedding cargo script in rustdoc output ([#1077])
+* Fix `clippy::io_other_error` warnings ([#1078])
+* Upgrade semver compatible dependencies ([#1076], [#1079], [#1080])
+
+[#1075]: https://github.com/lettre/lettre/pull/1075
+[#1076]: https://github.com/lettre/lettre/pull/1076
+[#1077]: https://github.com/lettre/lettre/pull/1077
+[#1078]: https://github.com/lettre/lettre/pull/1078
+[#1079]: https://github.com/lettre/lettre/pull/1079
+[#1080]: https://github.com/lettre/lettre/pull/1080
+[#1082]: https://github.com/lettre/lettre/pull/1082
+[#1083]: https://github.com/lettre/lettre/pull/1083
+[#1084]: https://github.com/lettre/lettre/pull/1084
+[#1086]: https://github.com/lettre/lettre/pull/1086
+[#1088]: https://github.com/lettre/lettre/pull/1088
+
 <a name="v0.11.15"></a>
 ### v0.11.15 (2025-03-10)
 

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 = "0.11.15"
+version = "0.11.17"
 description = "Email client"
 readme = "README.md"
 homepage = "https://lettre.rs"
@@ -20,7 +20,7 @@ maintenance = { status = "actively-developed" }
 
 [dependencies]
 email_address = { version = "0.2.1", default-features = false }
-chumsky = "0.9"
+nom = "8"
 idna = "1"
 
 ## tracing support
@@ -40,17 +40,17 @@ serde = { version = "1.0.110", features = ["derive"], optional = true }
 serde_json = { version = "1", optional = true }
 
 # smtp-transport
-nom = { version = "8", optional = true }
 hostname = { version = "0.4", optional = true } # feature
-socket2 = { version = "0.5.1", optional = true }
+socket2 = { version = "0.6", optional = true }
 url = { version = "2.4", optional = true }
 percent-encoding = { version = "2.3", optional = true }
 
 ## tls
 native-tls = { version = "0.2.9", optional = true } # feature
 rustls = { version = "0.23.18", default-features = false, features = ["logging", "std", "tls12"], optional = true }
+rustls-platform-verifier = { version = "0.6.0", optional = true }
 rustls-native-certs = { version = "0.8", optional = true }
-webpki-roots = { version = "0.26", optional = true }
+webpki-roots = { version = "1.0.0", optional = true }
 boring = { version = "4", optional = true }
 
 # async
@@ -73,6 +73,7 @@ sha2 = { version = "0.10", features = ["oid"], optional = true }
 rsa = { version = "0.9", optional = true }
 ed25519-dalek = { version = "2", optional = true }
 
+[target.'cfg(target_arch = "wasm32")'.dependencies]
 ## web-time for wasm support
 web-time = { version = "1.1.0", optional = true }
 
@@ -105,7 +106,7 @@ mime03 = ["dep:mime"]
 file-transport = ["dep:uuid", "tokio1_crate?/fs", "tokio1_crate?/io-util"]
 file-transport-envelope = ["serde", "dep:serde_json", "file-transport"]
 sendmail-transport = ["tokio1_crate?/process", "tokio1_crate?/io-util", "async-std?/unstable"]
-smtp-transport = ["dep:base64", "dep:nom", "dep:socket2", "dep:url", "dep:percent-encoding", "tokio1_crate?/rt", "tokio1_crate?/time", "tokio1_crate?/net"]
+smtp-transport = ["dep:base64", "dep:socket2", "dep:url", "dep:percent-encoding", "tokio1_crate?/rt", "tokio1_crate?/time", "tokio1_crate?/net"]
 
 pool = ["dep:futures-util"]
 

README.md

@@ -28,8 +28,8 @@
 </div>
 
 <div align="center">
-  <a href="https://deps.rs/crate/lettre/0.11.15">
-    <img src="https://deps.rs/crate/lettre/0.11.15/status.svg"
+  <a href="https://deps.rs/crate/lettre/0.11.17">
+    <img src="https://deps.rs/crate/lettre/0.11.17/status.svg"
       alt="dependency status" />
   </a>
 </div>
@@ -73,9 +73,9 @@ 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())
+        .from(Mailbox::new("NoBody".to_owned(), "nobody@domain.tld".parse().unwrap()))
+        .reply_to(Mailbox::new("Yuin".to_owned(), "yuin@domain.tld".parse().unwrap()))
+        .to(Mailbox::new("Hei".to_owned(), "hei@domain.tld".parse().unwrap()))
         .subject("Happy new year")
         .header(ContentType::TEXT_PLAIN)
         .body(String::from("Be happy!"))

src/address/envelope.rs

@@ -163,6 +163,7 @@ impl Envelope {
 }
 
 #[cfg(feature = "builder")]
+#[cfg_attr(docsrs, doc(cfg(feature = "builder")))]
 impl TryFrom<&Headers> for Envelope {
     type Error = Error;
 

src/lib.rs

@@ -93,17 +93,20 @@
 //! When the `rustls` feature is enabled, one of the following verification backends
 //! MUST also be enabled.
 //!
-//! * **rustls-native-certs**: verify TLS certificates using the platform's native certificate store (see [`rustls-native-certs`])
+//! * **rustls-platform-verifier**: verify TLS certificate using the OS's native certificate store (see [`rustls-platform-verifier`])
+//! * **rustls-native-certs**: verify TLS certificates using the platform's native certificate store (see [`rustls-native-certs`]) - when in doubt use `rustls-platform-verifier`
 //! * **webpki-roots**: verify TLS certificates against Mozilla's root certificates (see [`webpki-roots`])
 //!
-//! For the `rustls-native-certs` backend to work correctly, the following packages
-//! will need to be installed in order for the build stage and the compiled program
-//! to run properly.
+//! The following packages will need to be installed in order for the build
+//! stage and the compiled program to run properly.
 //!
-//! | Distro       | Build-time packages        | Runtime packages             |
-//! | ------------ | -------------------------- | ---------------------------- |
-//! | Debian       | none                       | `ca-certificates`            |
-//! | Alpine Linux | none                       | `ca-certificates`            |
+//! | Verification backend       | Distro       | Build-time packages        | Runtime packages             |
+//! | ---------------------      | ------------ | -------------------------- | ---------------------------- |
+//! | `rustls-platform-verifier` | Debian       | none                       | `ca-certificates`            |
+//! | `rustls-platform-verifier` | Alpine Linux | none                       | `ca-certificates`            |
+//! | `rustls-native-certs`      | Debian       | none                       | `ca-certificates`            |
+//! | `rustls-native-certs`      | Alpine Linux | none                       | `ca-certificates`            |
+//! | `webpki-roots`             | any          | none                       | none                         |
 //!
 //! ### Sendmail transport
 //!
@@ -151,6 +154,7 @@
 //! [AWS-LC]: https://github.com/aws/aws-lc
 //! [`aws-lc-rs`]: https://crates.io/crates/aws-lc-rs
 //! [`ring`]: https://crates.io/crates/ring
+//! [`rustls-platform-verifier`]: https://crates.io/crates/rustls-platform-verifier
 //! [`rustls-native-certs`]: https://crates.io/crates/rustls-native-certs
 //! [`webpki-roots`]: https://crates.io/crates/webpki-roots
 //! [Tokio 1.x]: https://docs.rs/tokio/1
@@ -158,7 +162,7 @@
 //! [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/0.11.15")]
+#![doc(html_root_url = "https://docs.rs/crate/lettre/0.11.17")]
 #![doc(html_favicon_url = "https://lettre.rs/favicon.ico")]
 #![doc(html_logo_url = "https://avatars0.githubusercontent.com/u/15113230?v=4")]
 #![forbid(unsafe_code)]
@@ -208,12 +212,13 @@ mod compiletime_checks {
 
     #[cfg(all(
         feature = "rustls",
+        not(feature = "rustls-platform-verifier"),
         not(feature = "rustls-native-certs"),
         not(feature = "webpki-roots")
     ))]
     compile_error!(
-        "feature `rustls` also requires either the `rustls-native-certs` or the `webpki-roots` feature to
-    be enabled"
+        "feature `rustls` also requires either the `rustls-platform-verifier`, the `rustls-native-certs`
+    or the `webpki-roots` feature to be enabled"
     );
 
     #[cfg(all(feature = "native-tls", feature = "boring-tls"))]

src/message/mailbox/parsers/rfc2234.rs

@@ -3,30 +3,34 @@
 //!
 //! [RFC2234]: https://datatracker.ietf.org/doc/html/rfc2234
 
-use chumsky::{error::Cheap, prelude::*};
+use nom::{
+    branch::alt,
+    character::complete::{char, satisfy},
+    IResult, Parser,
+};
 
 // 6.1  Core Rules
 // https://datatracker.ietf.org/doc/html/rfc2234#section-6.1
 
 // ALPHA          =  %x41-5A / %x61-7A   ; A-Z / a-z
-pub(super) fn alpha() -> impl Parser<char, char, Error = Cheap<char>> {
-    filter(|c: &char| c.is_ascii_alphabetic())
+pub(super) fn alpha(input: &str) -> IResult<&str, char> {
+    satisfy(|c| c.is_ascii_alphabetic()).parse(input)
 }
 
 // DIGIT          =  %x30-39
 //                        ; 0-9
-pub(super) fn digit() -> impl Parser<char, char, Error = Cheap<char>> {
-    filter(|c: &char| c.is_ascii_digit())
+pub(super) fn digit(input: &str) -> IResult<&str, char> {
+    satisfy(|c| c.is_ascii_digit()).parse(input)
 }
 
 // DQUOTE         =  %x22
 //                        ; " (Double Quote)
-pub(super) fn dquote() -> impl Parser<char, char, Error = Cheap<char>> {
-    just('"')
+pub(super) fn dquote(input: &str) -> IResult<&str, char> {
+    char('"').parse(input)
 }
 
 // WSP            =  SP / HTAB
 //                        ; white space
-pub(super) fn wsp() -> impl Parser<char, char, Error = Cheap<char>> {
-    choice((just(' '), just('\t')))
+pub(super) fn wsp(input: &str) -> IResult<&str, char> {
+    alt((char(' '), char('\t'))).parse(input)
 }

src/message/mailbox/parsers/rfc2822.rs

@@ -3,7 +3,14 @@
 //!
 //! [RFC2822]: https://datatracker.ietf.org/doc/html/rfc2822
 
-use chumsky::{error::Cheap, prelude::*};
+use nom::{
+    branch::alt,
+    character::complete::{char, satisfy},
+    combinator::{eof, map, opt},
+    multi::{fold_many0, fold_many1, many0, many1, separated_list0},
+    sequence::{delimited, pair, preceded, terminated},
+    IResult, Parser,
+};
 
 use super::{rfc2234, rfc5336};
 
@@ -15,8 +22,8 @@ use super::{rfc2234, rfc5336};
 //                         %d12 /          ;  carriage return, line feed,
 //                         %d14-31 /       ;  and white space characters
 //                         %d127
-fn no_ws_ctl() -> impl Parser<char, char, Error = Cheap<char>> {
-    filter(|c| matches!(u32::from(*c), 1..=8 | 11 | 12 | 14..=31 | 127))
+fn no_ws_ctl(input: &str) -> IResult<&str, char> {
+    satisfy(|c| matches!(u32::from(c), 1..=8 | 11 | 12 | 14..=31 | 127)).parse(input)
 }
 
 // text            =       %d1-9 /         ; Characters excluding CR and LF
@@ -24,16 +31,16 @@ fn no_ws_ctl() -> impl Parser<char, char, Error = Cheap<char>> {
 //                         %d12 /
 //                         %d14-127 /
 //                         obs-text
-fn text() -> impl Parser<char, char, Error = Cheap<char>> {
-    filter(|c| matches!(u32::from(*c), 1..=9 | 11 | 12 | 14..=127))
+fn text(input: &str) -> IResult<&str, char> {
+    satisfy(|c| matches!(u32::from(c), 1..=9 | 11 | 12 | 14..=127)).parse(input)
 }
 
 // 3.2.2. Quoted characters
 // https://datatracker.ietf.org/doc/html/rfc2822#section-3.2.2
 
 // quoted-pair     =       ("\" text) / obs-qp
-fn quoted_pair() -> impl Parser<char, char, Error = Cheap<char>> {
-    just('\\').ignore_then(text())
+fn quoted_pair(input: &str) -> IResult<&str, char> {
+    preceded(char('\\'), text).parse(input)
 }
 
 // 3.2.3. Folding white space and comments
@@ -41,17 +48,19 @@ fn quoted_pair() -> impl Parser<char, char, Error = Cheap<char>> {
 
 // FWS             =       ([*WSP CRLF] 1*WSP) /   ; Folding white space
 //                         obs-FWS
-pub(super) fn fws() -> impl Parser<char, Option<char>, Error = Cheap<char>> {
-    rfc2234::wsp()
-        .or_not()
-        .then_ignore(rfc2234::wsp().ignored().repeated())
+pub(super) fn fws(input: &str) -> IResult<&str, Option<char>> {
+    map(
+        pair(opt(rfc2234::wsp), many0(rfc2234::wsp)),
+        |(first, _rest)| first,
+    )
+    .parse(input)
 }
 
 // CFWS            =       *([FWS] comment) (([FWS] comment) / FWS)
-pub(super) fn cfws() -> impl Parser<char, Option<char>, Error = Cheap<char>> {
+pub(super) fn cfws(input: &str) -> IResult<&str, Option<char>> {
     // TODO: comment are not currently supported, so for now a cfws is
     // the same as a fws.
-    fws()
+    fws(input)
 }
 
 // 3.2.4. Atom
@@ -68,13 +77,13 @@ pub(super) fn cfws() -> impl Parser<char, Option<char>, Error = Cheap<char>> {
 //                         "`" / "{" /
 //                         "|" / "}" /
 //                         "~"
-pub(super) fn atext() -> impl Parser<char, char, Error = Cheap<char>> {
-    choice((
-        rfc2234::alpha(),
-        rfc2234::digit(),
-        filter(|c| {
+pub(super) fn atext(input: &str) -> IResult<&str, char> {
+    alt((
+        rfc2234::alpha,
+        rfc2234::digit,
+        satisfy(|c| {
             matches!(
-                *c,
+                c,
                 '!' | '#'
                     | '$'
                     | '%'
@@ -96,29 +105,64 @@ pub(super) fn atext() -> impl Parser<char, char, Error = Cheap<char>> {
             )
         }),
         // also allow non ASCII UTF8 chars
-        rfc5336::utf8_non_ascii(),
+        rfc5336::utf8_non_ascii,
     ))
+    .parse(input)
 }
 
 // atom            =       [CFWS] 1*atext [CFWS]
-pub(super) fn atom() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    cfws().chain(atext().repeated().at_least(1))
+pub(super) fn atom(input: &str) -> IResult<&str, String> {
+    map(
+        pair(
+            cfws,
+            fold_many1(atext, String::new, |mut acc, c| {
+                acc.push(c);
+                acc
+            }),
+        ),
+        |(cfws, mut chars)| {
+            if let Some(cfws) = cfws {
+                chars.insert(0, cfws);
+            }
+            chars
+        },
+    )
+    .parse(input)
 }
 
 // dot-atom        =       [CFWS] dot-atom-text [CFWS]
-pub(super) fn dot_atom() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    cfws().chain(dot_atom_text())
+pub(super) fn dot_atom(input: &str) -> IResult<&str, String> {
+    map(pair(cfws, dot_atom_text), |(_cfws, text)| text).parse(input)
 }
 
 // dot-atom-text   =       1*atext *("." 1*atext)
-pub(super) fn dot_atom_text() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    atext().repeated().at_least(1).chain(
-        just('.')
-            .chain(atext().repeated().at_least(1))
-            .repeated()
-            .at_least(1)
-            .flatten(),
+pub(super) fn dot_atom_text(input: &str) -> IResult<&str, String> {
+    map(
+        pair(
+            fold_many1(atext, String::new, |mut acc, c| {
+                acc.push(c);
+                acc
+            }),
+            many0(map(
+                pair(
+                    char('.'),
+                    fold_many1(atext, String::new, |mut acc, c| {
+                        acc.push(c);
+                        acc
+                    }),
+                ),
+                |(dot, chars)| format!("{dot}{chars}"),
+            )),
+        ),
+        |(first, rest)| {
+            let mut result = first;
+            for part in rest {
+                result.push_str(&part);
+            }
+            result
+        },
     )
+    .parse(input)
 }
 
 // 3.2.5. Quoted strings
@@ -129,122 +173,168 @@ pub(super) fn dot_atom_text() -> impl Parser<char, Vec<char>, Error = Cheap<char
 //                         %d33 /          ; The rest of the US-ASCII
 //                         %d35-91 /       ;  characters not including "\"
 //                         %d93-126        ;  or the quote character
-fn qtext() -> impl Parser<char, char, Error = Cheap<char>> {
-    choice((
-        filter(|c| matches!(u32::from(*c), 33 | 35..=91 | 93..=126)),
-        no_ws_ctl(),
+fn qtext(input: &str) -> IResult<&str, char> {
+    alt((
+        satisfy(|c| matches!(u32::from(c), 33 | 35..=91 | 93..=126)),
+        no_ws_ctl,
     ))
+    .parse(input)
 }
 
 // qcontent        =       qtext / quoted-pair
-pub(super) fn qcontent() -> impl Parser<char, char, Error = Cheap<char>> {
-    choice((qtext(), quoted_pair(), rfc5336::utf8_non_ascii()))
+pub(super) fn qcontent(input: &str) -> IResult<&str, char> {
+    alt((qtext, quoted_pair, rfc5336::utf8_non_ascii)).parse(input)
 }
 
 // quoted-string   =       [CFWS]
 //                         DQUOTE *([FWS] qcontent) [FWS] DQUOTE
 //                         [CFWS]
-fn quoted_string() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    rfc2234::dquote()
-        .ignore_then(fws().chain(qcontent()).repeated().flatten())
-        .then_ignore(text::whitespace())
-        .then_ignore(rfc2234::dquote())
+fn quoted_string(input: &str) -> IResult<&str, String> {
+    map(
+        delimited(
+            rfc2234::dquote,
+            fold_many0(
+                map(pair(fws, qcontent), |(_fws, c)| c),
+                String::new,
+                |mut acc, c| {
+                    acc.push(c);
+                    acc
+                },
+            ),
+            preceded(many0(satisfy(char::is_whitespace)), rfc2234::dquote),
+        ),
+        |s| s,
+    )
+    .parse(input)
 }
 
 // 3.2.6. Miscellaneous tokens
 // https://datatracker.ietf.org/doc/html/rfc2822#section-3.2.6
 
 // word            =       atom / quoted-string
-fn word() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    choice((quoted_string(), atom()))
+fn word(input: &str) -> IResult<&str, String> {
+    alt((quoted_string, atom)).parse(input)
 }
 
 // phrase          =       1*word / obs-phrase
-fn phrase() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    choice((obs_phrase(), word().repeated().at_least(1).flatten()))
+fn phrase(input: &str) -> IResult<&str, String> {
+    alt((obs_phrase, map(many1(word), |words| words.join(" ")))).parse(input)
 }
 
 // 3.4. Address Specification
 // https://datatracker.ietf.org/doc/html/rfc2822#section-3.4
 
 // 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())
+pub(crate) fn mailbox(input: &str) -> IResult<&str, (Option<String>, (String, String))> {
+    terminated(alt((name_addr, map(addr_spec, |addr| (None, addr)))), eof).parse(input)
 }
 
 // name-addr       =       [display-name] angle-addr
-fn name_addr() -> impl Parser<char, (Option<String>, (String, String)), Error = Cheap<char>> {
-    display_name().collect().or_not().then(angle_addr())
+fn name_addr(input: &str) -> IResult<&str, (Option<String>, (String, String))> {
+    pair(opt(display_name), angle_addr).parse(input)
 }
 
 // angle-addr      =       [CFWS] "<" addr-spec ">" [CFWS] / obs-angle-addr
-fn angle_addr() -> impl Parser<char, (String, String), Error = Cheap<char>> {
-    addr_spec()
-        .delimited_by(just('<').ignored(), just('>').ignored())
-        .padded()
+fn angle_addr(input: &str) -> IResult<&str, (String, String)> {
+    delimited((cfws, char('<')), addr_spec, (char('>'), cfws)).parse(input)
 }
 
 // display-name    =       phrase
-fn display_name() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    phrase()
+fn display_name(input: &str) -> IResult<&str, String> {
+    phrase(input)
 }
 
 // mailbox-list    =       (mailbox *("," mailbox)) / obs-mbox-list
-pub(crate) fn mailbox_list(
-) -> impl Parser<char, Vec<(Option<String>, (String, String))>, Error = Cheap<char>> {
-    choice((name_addr(), addr_spec().map(|addr| (None, addr))))
-        .separated_by(just(',').padded())
-        .then_ignore(end())
+#[allow(clippy::type_complexity)]
+pub(crate) fn mailbox_list(input: &str) -> IResult<&str, Vec<(Option<String>, (String, String))>> {
+    terminated(
+        separated_list0(
+            delimited(
+                many0(satisfy(char::is_whitespace)),
+                char(','),
+                many0(satisfy(char::is_whitespace)),
+            ),
+            alt((name_addr, map(addr_spec, |addr| (None, addr)))),
+        ),
+        eof,
+    )
+    .parse(input)
 }
 
 // 3.4.1. Addr-spec specification
 // https://datatracker.ietf.org/doc/html/rfc2822#section-3.4.1
 
 // addr-spec       =       local-part "@" domain
-pub(super) fn addr_spec() -> impl Parser<char, (String, String), Error = Cheap<char>> {
-    local_part()
-        .collect()
-        .then_ignore(just('@'))
-        .then(domain().collect())
+pub(super) fn addr_spec(input: &str) -> IResult<&str, (String, String)> {
+    pair(terminated(local_part, char('@')), domain).parse(input)
 }
 
 // local-part      =       dot-atom / quoted-string / obs-local-part
-pub(super) fn local_part() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    choice((dot_atom(), quoted_string(), obs_local_part()))
+pub(super) fn local_part(input: &str) -> IResult<&str, String> {
+    alt((dot_atom, quoted_string, obs_local_part)).parse(input)
 }
 
 // domain          =       dot-atom / domain-literal / obs-domain
-pub(super) fn domain() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
+pub(super) fn domain(input: &str) -> IResult<&str, String> {
     // NOTE: omitting domain-literal since it may never be used
-    choice((dot_atom(), obs_domain()))
+    alt((dot_atom, obs_domain)).parse(input)
 }
 
 // 4.1. Miscellaneous obsolete tokens
 // https://datatracker.ietf.org/doc/html/rfc2822#section-4.1
 
 // obs-phrase      =       word *(word / "." / CFWS)
-fn obs_phrase() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
+fn obs_phrase(input: &str) -> IResult<&str, String> {
     // NOTE: the CFWS is already captured by the word, no need to add
     // it there.
-    word().chain(
-        choice((word(), just('.').repeated().exactly(1)))
-            .repeated()
-            .flatten(),
+    map(
+        pair(word, many0(alt((word, map(char('.'), |c| c.to_string()))))),
+        |(first, rest)| {
+            let mut result = first;
+            for part in rest {
+                result.push_str(&part);
+            }
+            result
+        },
     )
+    .parse(input)
 }
 
 // 4.4. Obsolete Addressing
 // https://datatracker.ietf.org/doc/html/rfc2822#section-4.4
 
 // obs-local-part  =       word *("." word)
-pub(super) fn obs_local_part() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    word().chain(just('.').chain(word()).repeated().flatten())
+pub(super) fn obs_local_part(input: &str) -> IResult<&str, String> {
+    map(
+        pair(
+            word,
+            many0(map(pair(char('.'), word), |(dot, w)| format!("{dot}{w}"))),
+        ),
+        |(first, rest)| {
+            let mut result = first;
+            for part in rest {
+                result.push_str(&part);
+            }
+            result
+        },
+    )
+    .parse(input)
 }
 
 // obs-domain      =       atom *("." atom)
-pub(super) fn obs_domain() -> impl Parser<char, Vec<char>, Error = Cheap<char>> {
-    atom().chain(just('.').chain(atom()).repeated().flatten())
+pub(super) fn obs_domain(input: &str) -> IResult<&str, String> {
+    map(
+        pair(
+            atom,
+            many0(map(pair(char('.'), atom), |(dot, a)| format!("{dot}{a}"))),
+        ),
+        |(first, rest)| {
+            let mut result = first;
+            for part in rest {
+                result.push_str(&part);
+            }
+            result
+        },
+    )
+    .parse(input)
 }

src/message/mailbox/parsers/rfc5336.rs

@@ -3,7 +3,7 @@
 //!
 //! [RFC5336]: https://datatracker.ietf.org/doc/html/rfc5336
 
-use chumsky::{error::Cheap, prelude::*};
+use nom::{character::complete::satisfy, IResult, Parser};
 
 // 3.3.  Extended Mailbox Address Syntax
 // https://datatracker.ietf.org/doc/html/rfc5336#section-3.3
@@ -12,6 +12,6 @@ use chumsky::{error::Cheap, prelude::*};
 // UTF8-2 =  <See Section 4 of RFC 3629>
 // UTF8-3 =  <See Section 4 of RFC 3629>
 // UTF8-4 =  <See Section 4 of RFC 3629>
-pub(super) fn utf8_non_ascii() -> impl Parser<char, char, Error = Cheap<char>> {
-    filter(|c: &char| c.len_utf8() > 1)
+pub(super) fn utf8_non_ascii(input: &str) -> IResult<&str, char> {
+    satisfy(|c| c.len_utf8() > 1).parse(input)
 }

src/message/mailbox/types.rs

@@ -5,7 +5,6 @@ use std::{
     str::FromStr,
 };
 
-use chumsky::prelude::*;
 use email_encoding::headers::writer::EmailWriter;
 
 use super::parsers;
@@ -114,7 +113,7 @@ impl FromStr for Mailbox {
     type Err = AddressError;
 
     fn from_str(src: &str) -> Result<Mailbox, Self::Err> {
-        let (name, (user, domain)) = parsers::mailbox().parse(src).map_err(|_errs| {
+        let (_rest, (name, (user, domain))) = parsers::mailbox(src).map_err(|_errs| {
             // TODO: improve error management
             AddressError::InvalidInput
         })?;
@@ -345,7 +344,7 @@ impl FromStr for Mailboxes {
     fn from_str(src: &str) -> Result<Self, Self::Err> {
         let mut mailboxes = Vec::new();
 
-        let parsed_mailboxes = parsers::mailbox_list().parse(src).map_err(|_errs| {
+        let (_rest, parsed_mailboxes) = parsers::mailbox_list(src).map_err(|_errs| {
             // TODO: improve error management
             AddressError::InvalidInput
         })?;

src/time.rs

@@ -1,6 +1,6 @@
 use std::time::SystemTime;
 
-#[cfg(feature = "web")]
+#[cfg(all(feature = "web", target_arch = "wasm32"))]
 pub(crate) fn now() -> SystemTime {
     fn to_std_systemtime(time: web_time::SystemTime) -> std::time::SystemTime {
         let duration = time
@@ -18,7 +18,7 @@ pub(crate) fn now() -> SystemTime {
     to_std_systemtime(web_time::SystemTime::now())
 }
 
-#[cfg(not(feature = "web"))]
+#[cfg(not(all(feature = "web", target_arch = "wasm32")))]
 pub(crate) fn now() -> SystemTime {
     // FIXME: change to #[expect(clippy::disallowed_methods, reason = "the `web` feature is disabled")]
     #[allow(clippy::disallowed_methods)]

src/transport/file/error.rs

@@ -34,6 +34,7 @@ impl Error {
 
     /// Returns true if the error is an envelope serialization or deserialization error
     #[cfg(feature = "file-transport-envelope")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "file-transport-envelope")))]
     pub fn is_envelope(&self) -> bool {
         matches!(self.inner.kind, Kind::Envelope)
     }

src/transport/file/mod.rs

@@ -173,7 +173,7 @@ pub struct FileTransport {
 }
 
 /// Asynchronously writes the content and the envelope information to a file
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[cfg_attr(docsrs, doc(cfg(any(feature = "tokio1", feature = "async-std1"))))]
 #[cfg(any(feature = "async-std1", feature = "tokio1"))]
@@ -199,6 +199,7 @@ impl FileTransport {
     /// Writes the email content in eml format and the envelope
     /// in json format.
     #[cfg(feature = "file-transport-envelope")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "file-transport-envelope")))]
     pub fn with_envelope<P: AsRef<Path>>(path: P) -> FileTransport {
         FileTransport {
             path: PathBuf::from(path.as_ref()),
@@ -211,6 +212,7 @@ impl FileTransport {
     ///
     /// Reads the envelope and the raw message content.
     #[cfg(feature = "file-transport-envelope")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "file-transport-envelope")))]
     pub fn read(&self, email_id: &str) -> Result<(Envelope, Vec<u8>), Error> {
         use std::fs;
 
@@ -249,6 +251,7 @@ where
     /// Writes the email content in eml format and the envelope
     /// in json format.
     #[cfg(feature = "file-transport-envelope")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "file-transport-envelope")))]
     pub fn with_envelope<P: AsRef<Path>>(path: P) -> Self {
         Self {
             inner: FileTransport::with_envelope(path),
@@ -260,6 +263,7 @@ where
     ///
     /// Reads the envelope and the raw message content.
     #[cfg(feature = "file-transport-envelope")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "file-transport-envelope")))]
     pub async fn read(&self, email_id: &str) -> Result<(Envelope, Vec<u8>), Error> {
         let eml_file = self.inner.path.join(format!("{email_id}.eml"));
         let eml = E::fs_read(&eml_file).await.map_err(error::io)?;
@@ -272,6 +276,16 @@ where
     }
 }
 
+#[cfg(any(feature = "async-std1", feature = "tokio1"))]
+impl<E: Executor> Clone for AsyncFileTransport<E> {
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker_: PhantomData,
+        }
+    }
+}
+
 impl Transport for FileTransport {
     type Ok = Id;
     type Error = Error;

src/transport/smtp/async_transport.rs

@@ -234,7 +234,7 @@ where
     /// a proper URL encoder, like the following cargo script:
     ///
     /// ```rust
-    /// # let _ = r#"
+    /// # const TOML: &str = r#"
     /// #!/usr/bin/env cargo
     ///
     /// //! ```cargo

src/transport/smtp/authentication.rs

@@ -19,9 +19,6 @@ pub struct Credentials {
 
 impl Credentials {
     /// Create a `Credentials` struct from username and password
-    ///
-    /// When using [`Mechanism::Xoauth2`], `password` is the raw
-    /// bearer access token.
     pub fn new(username: String, password: String) -> Credentials {
         Credentials {
             authentication_identity: username,

src/transport/smtp/client/async_connection.rs

@@ -54,6 +54,7 @@ impl AsyncSmtpConnection {
     ///
     /// Sends EHLO and parses server information
     #[cfg(feature = "tokio1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
     pub async fn connect_with_transport(
         stream: Box<dyn AsyncTokioStream>,
         hello_name: &ClientId,
@@ -94,6 +95,7 @@ impl AsyncSmtpConnection {
     /// # }
     /// ```
     #[cfg(feature = "tokio1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
     pub async fn connect_tokio1<T: tokio1_crate::net::ToSocketAddrs>(
         server: T,
         timeout: Option<Duration>,
@@ -112,6 +114,7 @@ impl AsyncSmtpConnection {
     ///
     /// Sends EHLO and parses server information
     #[cfg(feature = "async-std1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async-std1")))]
     pub async fn connect_asyncstd1<T: async_std::net::ToSocketAddrs>(
         server: T,
         timeout: Option<Duration>,
@@ -376,6 +379,10 @@ impl AsyncSmtpConnection {
 
     /// The X509 certificate of the server (DER encoded)
     #[cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+    )]
     pub fn peer_certificate(&self) -> Result<Vec<u8>, Error> {
         self.stream.get_ref().peer_certificate()
     }
@@ -392,12 +399,14 @@ impl AsyncSmtpConnection {
     /// as the TLSA records match the leaf or issuer certificates.
     /// It cannot be called on non Boring TLS streams.
     #[cfg(feature = "boring-tls")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "boring-tls")))]
     pub fn tls_verify_result(&self) -> Result<(), Error> {
         self.stream.get_ref().tls_verify_result()
     }
 
     /// All the X509 certificates of the chain (DER encoded)
     #[cfg(any(feature = "rustls", feature = "boring-tls"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "rustls", feature = "boring-tls"))))]
     pub fn certificate_chain(&self) -> Result<Vec<Vec<u8>>, Error> {
         self.stream.get_ref().certificate_chain()
     }

src/transport/smtp/client/async_net.rs

@@ -9,11 +9,11 @@ use std::{
 #[cfg(feature = "async-std1")]
 use async_std::net::{TcpStream as AsyncStd1TcpStream, ToSocketAddrs as AsyncStd1ToSocketAddrs};
 use futures_io::{
-    AsyncRead as FuturesAsyncRead, AsyncWrite as FuturesAsyncWrite, Error as IoError, ErrorKind,
+    AsyncRead as FuturesAsyncRead, AsyncWrite as FuturesAsyncWrite, Error as IoError,
     Result as IoResult,
 };
 #[cfg(feature = "async-std1-rustls")]
-use futures_rustls::client::TlsStream as AsyncStd1RustlsTlsStream;
+use futures_rustls::client::TlsStream as AsyncStd1RustlsStream;
 #[cfg(any(feature = "tokio1-rustls", feature = "async-std1-rustls"))]
 use rustls::pki_types::ServerName;
 #[cfg(feature = "tokio1-boring-tls")]
@@ -28,7 +28,7 @@ use tokio1_crate::net::{
 #[cfg(feature = "tokio1-native-tls")]
 use tokio1_native_tls_crate::TlsStream as Tokio1TlsStream;
 #[cfg(feature = "tokio1-rustls")]
-use tokio1_rustls::client::TlsStream as Tokio1RustlsTlsStream;
+use tokio1_rustls::client::TlsStream as Tokio1RustlsStream;
 
 #[cfg(any(
     feature = "tokio1-native-tls",
@@ -79,7 +79,7 @@ enum InnerAsyncNetworkStream {
     Tokio1NativeTls(Tokio1TlsStream<Box<dyn AsyncTokioStream>>),
     /// Encrypted Tokio 1.x TCP stream
     #[cfg(feature = "tokio1-rustls")]
-    Tokio1RustlsTls(Tokio1RustlsTlsStream<Box<dyn AsyncTokioStream>>),
+    Tokio1Rustls(Tokio1RustlsStream<Box<dyn AsyncTokioStream>>),
     /// Encrypted Tokio 1.x TCP stream
     #[cfg(feature = "tokio1-boring-tls")]
     Tokio1BoringTls(Tokio1SslStream<Box<dyn AsyncTokioStream>>),
@@ -88,7 +88,7 @@ enum InnerAsyncNetworkStream {
     AsyncStd1Tcp(AsyncStd1TcpStream),
     /// Encrypted Tokio 1.x TCP stream
     #[cfg(feature = "async-std1-rustls")]
-    AsyncStd1RustlsTls(AsyncStd1RustlsTlsStream<AsyncStd1TcpStream>),
+    AsyncStd1Rustls(AsyncStd1RustlsStream<AsyncStd1TcpStream>),
     /// Can't be built
     None,
 }
@@ -113,17 +113,16 @@ impl AsyncNetworkStream {
                 s.get_ref().get_ref().get_ref().peer_addr()
             }
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(s) => s.get_ref().0.peer_addr(),
+            InnerAsyncNetworkStream::Tokio1Rustls(s) => s.get_ref().0.peer_addr(),
             #[cfg(feature = "tokio1-boring-tls")]
             InnerAsyncNetworkStream::Tokio1BoringTls(s) => s.get_ref().peer_addr(),
             #[cfg(feature = "async-std1")]
             InnerAsyncNetworkStream::AsyncStd1Tcp(s) => s.peer_addr(),
             #[cfg(feature = "async-std1-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => s.get_ref().0.peer_addr(),
+            InnerAsyncNetworkStream::AsyncStd1Rustls(s) => s.get_ref().0.peer_addr(),
             InnerAsyncNetworkStream::None => {
                 debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
-                Err(IoError::new(
-                    ErrorKind::Other,
+                Err(IoError::other(
                     "InnerAsyncNetworkStream::None must never be built",
                 ))
             }
@@ -131,11 +130,13 @@ impl AsyncNetworkStream {
     }
 
     #[cfg(feature = "tokio1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
     pub fn use_existing_tokio1(stream: Box<dyn AsyncTokioStream>) -> AsyncNetworkStream {
         AsyncNetworkStream::new(InnerAsyncNetworkStream::Tokio1Tcp(stream))
     }
 
     #[cfg(feature = "tokio1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "tokio1")))]
     pub async fn connect_tokio1<T: Tokio1ToSocketAddrs>(
         server: T,
         timeout: Option<Duration>,
@@ -202,6 +203,7 @@ impl AsyncNetworkStream {
     }
 
     #[cfg(feature = "async-std1")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "async-std1")))]
     pub async fn connect_asyncstd1<T: AsyncStd1ToSocketAddrs>(
         server: T,
         timeout: Option<Duration>,
@@ -321,7 +323,7 @@ impl AsyncNetworkStream {
 
         match tls_parameters.connector {
             #[cfg(feature = "native-tls")]
-            InnerTlsParameters::NativeTls(connector) => {
+            InnerTlsParameters::NativeTls { connector } => {
                 #[cfg(not(feature = "tokio1-native-tls"))]
                 panic!("built without the tokio1-native-tls feature");
 
@@ -338,7 +340,7 @@ impl AsyncNetworkStream {
                 };
             }
             #[cfg(feature = "rustls")]
-            InnerTlsParameters::RustlsTls(config) => {
+            InnerTlsParameters::Rustls { config } => {
                 #[cfg(not(feature = "tokio1-rustls"))]
                 panic!("built without the tokio1-rustls feature");
 
@@ -354,18 +356,21 @@ impl AsyncNetworkStream {
                         .connect(domain.to_owned(), tcp_stream)
                         .await
                         .map_err(error::connection)?;
-                    Ok(InnerAsyncNetworkStream::Tokio1RustlsTls(stream))
+                    Ok(InnerAsyncNetworkStream::Tokio1Rustls(stream))
                 };
             }
             #[cfg(feature = "boring-tls")]
-            InnerTlsParameters::BoringTls(connector) => {
+            InnerTlsParameters::BoringTls {
+                connector,
+                accept_invalid_hostnames,
+            } => {
                 #[cfg(not(feature = "tokio1-boring-tls"))]
                 panic!("built without the tokio1-boring-tls feature");
 
                 #[cfg(feature = "tokio1-boring-tls")]
                 return {
                     let mut config = connector.configure().map_err(error::connection)?;
-                    config.set_verify_hostname(tls_parameters.accept_invalid_hostnames);
+                    config.set_verify_hostname(accept_invalid_hostnames);
 
                     let stream = tokio1_boring::connect(config, &domain, tcp_stream)
                         .await
@@ -386,11 +391,11 @@ impl AsyncNetworkStream {
 
         match tls_parameters.connector {
             #[cfg(feature = "native-tls")]
-            InnerTlsParameters::NativeTls(connector) => {
+            InnerTlsParameters::NativeTls { connector } => {
                 panic!("native-tls isn't supported with async-std yet. See https://github.com/lettre/lettre/pull/531#issuecomment-757893531");
             }
             #[cfg(feature = "rustls")]
-            InnerTlsParameters::RustlsTls(config) => {
+            InnerTlsParameters::Rustls { config } => {
                 #[cfg(not(feature = "async-std1-rustls"))]
                 panic!("built without the async-std1-rustls feature");
 
@@ -406,11 +411,11 @@ impl AsyncNetworkStream {
                         .connect(domain.to_owned(), tcp_stream)
                         .await
                         .map_err(error::connection)?;
-                    Ok(InnerAsyncNetworkStream::AsyncStd1RustlsTls(stream))
+                    Ok(InnerAsyncNetworkStream::AsyncStd1Rustls(stream))
                 };
             }
             #[cfg(feature = "boring-tls")]
-            InnerTlsParameters::BoringTls(connector) => {
+            InnerTlsParameters::BoringTls { .. } => {
                 panic!("boring-tls isn't supported with async-std yet.");
             }
         }
@@ -423,18 +428,19 @@ impl AsyncNetworkStream {
             #[cfg(feature = "tokio1-native-tls")]
             InnerAsyncNetworkStream::Tokio1NativeTls(_) => true,
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(_) => true,
+            InnerAsyncNetworkStream::Tokio1Rustls(_) => true,
             #[cfg(feature = "tokio1-boring-tls")]
             InnerAsyncNetworkStream::Tokio1BoringTls(_) => true,
             #[cfg(feature = "async-std1")]
             InnerAsyncNetworkStream::AsyncStd1Tcp(_) => false,
             #[cfg(feature = "async-std1-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(_) => true,
+            InnerAsyncNetworkStream::AsyncStd1Rustls(_) => true,
             InnerAsyncNetworkStream::None => false,
         }
     }
 
     #[cfg(feature = "boring-tls")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "boring-tls")))]
     pub fn tls_verify_result(&self) -> Result<(), Error> {
         match &self.inner {
             #[cfg(feature = "tokio1")]
@@ -444,7 +450,7 @@ impl AsyncNetworkStream {
             #[cfg(feature = "tokio1-native-tls")]
             InnerAsyncNetworkStream::Tokio1NativeTls(_) => panic!("Unsupported"),
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(_) => panic!("Unsupported"),
+            InnerAsyncNetworkStream::Tokio1Rustls(_) => panic!("Unsupported"),
             #[cfg(feature = "tokio1-boring-tls")]
             InnerAsyncNetworkStream::Tokio1BoringTls(stream) => {
                 stream.ssl().verify_result().map_err(error::tls)
@@ -454,10 +460,11 @@ impl AsyncNetworkStream {
                 Err(error::client("Connection is not encrypted"))
             }
             #[cfg(feature = "async-std1-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(_) => panic!("Unsupported"),
+            InnerAsyncNetworkStream::AsyncStd1Rustls(_) => panic!("Unsupported"),
             InnerAsyncNetworkStream::None => panic!("InnerNetworkStream::None must never be built"),
         }
     }
+
     pub fn certificate_chain(&self) -> Result<Vec<Vec<u8>>, Error> {
         match &self.inner {
             #[cfg(feature = "tokio1")]
@@ -467,7 +474,7 @@ impl AsyncNetworkStream {
             #[cfg(feature = "tokio1-native-tls")]
             InnerAsyncNetworkStream::Tokio1NativeTls(_) => panic!("Unsupported"),
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(stream) => Ok(stream
+            InnerAsyncNetworkStream::Tokio1Rustls(stream) => Ok(stream
                 .get_ref()
                 .1
                 .peer_certificates()
@@ -488,7 +495,7 @@ impl AsyncNetworkStream {
                 Err(error::client("Connection is not encrypted"))
             }
             #[cfg(feature = "async-std1-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(stream) => Ok(stream
+            InnerAsyncNetworkStream::AsyncStd1Rustls(stream) => Ok(stream
                 .get_ref()
                 .1
                 .peer_certificates()
@@ -515,7 +522,7 @@ impl AsyncNetworkStream {
                 .to_der()
                 .map_err(error::tls)?),
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(stream) => Ok(stream
+            InnerAsyncNetworkStream::Tokio1Rustls(stream) => Ok(stream
                 .get_ref()
                 .1
                 .peer_certificates()
@@ -535,7 +542,7 @@ impl AsyncNetworkStream {
                 Err(error::client("Connection is not encrypted"))
             }
             #[cfg(feature = "async-std1-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(stream) => Ok(stream
+            InnerAsyncNetworkStream::AsyncStd1Rustls(stream) => Ok(stream
                 .get_ref()
                 .1
                 .peer_certificates()
@@ -575,7 +582,7 @@ impl FuturesAsyncRead for AsyncNetworkStream {
                 }
             }
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(s) => {
+            InnerAsyncNetworkStream::Tokio1Rustls(s) => {
                 let mut b = Tokio1ReadBuf::new(buf);
                 match Pin::new(s).poll_read(cx, &mut b) {
                     Poll::Ready(Ok(())) => Poll::Ready(Ok(b.filled().len())),
@@ -595,7 +602,7 @@ impl FuturesAsyncRead for AsyncNetworkStream {
             #[cfg(feature = "async-std1")]
             InnerAsyncNetworkStream::AsyncStd1Tcp(s) => Pin::new(s).poll_read(cx, buf),
             #[cfg(feature = "async-std1-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_read(cx, buf),
+            InnerAsyncNetworkStream::AsyncStd1Rustls(s) => Pin::new(s).poll_read(cx, buf),
             InnerAsyncNetworkStream::None => {
                 debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                 Poll::Ready(Ok(0))
@@ -617,13 +624,13 @@ impl FuturesAsyncWrite for AsyncNetworkStream {
             #[cfg(feature = "tokio1-native-tls")]
             InnerAsyncNetworkStream::Tokio1NativeTls(s) => Pin::new(s).poll_write(cx, buf),
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(s) => Pin::new(s).poll_write(cx, buf),
+            InnerAsyncNetworkStream::Tokio1Rustls(s) => Pin::new(s).poll_write(cx, buf),
             #[cfg(feature = "tokio1-boring-tls")]
             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-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_write(cx, buf),
+            InnerAsyncNetworkStream::AsyncStd1Rustls(s) => Pin::new(s).poll_write(cx, buf),
             InnerAsyncNetworkStream::None => {
                 debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                 Poll::Ready(Ok(0))
@@ -638,13 +645,13 @@ impl FuturesAsyncWrite for AsyncNetworkStream {
             #[cfg(feature = "tokio1-native-tls")]
             InnerAsyncNetworkStream::Tokio1NativeTls(s) => Pin::new(s).poll_flush(cx),
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(s) => Pin::new(s).poll_flush(cx),
+            InnerAsyncNetworkStream::Tokio1Rustls(s) => Pin::new(s).poll_flush(cx),
             #[cfg(feature = "tokio1-boring-tls")]
             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-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_flush(cx),
+            InnerAsyncNetworkStream::AsyncStd1Rustls(s) => Pin::new(s).poll_flush(cx),
             InnerAsyncNetworkStream::None => {
                 debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                 Poll::Ready(Ok(()))
@@ -659,13 +666,13 @@ impl FuturesAsyncWrite for AsyncNetworkStream {
             #[cfg(feature = "tokio1-native-tls")]
             InnerAsyncNetworkStream::Tokio1NativeTls(s) => Pin::new(s).poll_shutdown(cx),
             #[cfg(feature = "tokio1-rustls")]
-            InnerAsyncNetworkStream::Tokio1RustlsTls(s) => Pin::new(s).poll_shutdown(cx),
+            InnerAsyncNetworkStream::Tokio1Rustls(s) => Pin::new(s).poll_shutdown(cx),
             #[cfg(feature = "tokio1-boring-tls")]
             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-rustls")]
-            InnerAsyncNetworkStream::AsyncStd1RustlsTls(s) => Pin::new(s).poll_close(cx),
+            InnerAsyncNetworkStream::AsyncStd1Rustls(s) => Pin::new(s).poll_close(cx),
             InnerAsyncNetworkStream::None => {
                 debug_assert!(false, "InnerAsyncNetworkStream::None must never be built");
                 Poll::Ready(Ok(()))

src/transport/smtp/client/connection.rs

@@ -300,6 +300,10 @@ impl SmtpConnection {
 
     /// The X509 certificate of the server (DER encoded)
     #[cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+    )]
     pub fn peer_certificate(&self) -> Result<Vec<u8>, Error> {
         self.stream.get_ref().peer_certificate()
     }
@@ -316,12 +320,14 @@ impl SmtpConnection {
     /// as the TLSA records match the leaf or issuer certificates.
     /// It cannot be called on non Boring TLS streams.
     #[cfg(feature = "boring-tls")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "boring-tls")))]
     pub fn tls_verify_result(&self) -> Result<(), Error> {
         self.stream.get_ref().tls_verify_result()
     }
 
     /// All the X509 certificates of the chain (DER encoded)
     #[cfg(any(feature = "rustls", feature = "boring-tls"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "rustls", feature = "boring-tls"))))]
     pub fn certificate_chain(&self) -> Result<Vec<Vec<u8>>, Error> {
         self.stream.get_ref().certificate_chain()
     }

src/transport/smtp/client/net.rs

@@ -37,7 +37,7 @@ enum InnerNetworkStream {
     NativeTls(TlsStream<TcpStream>),
     /// Encrypted TCP stream
     #[cfg(feature = "rustls")]
-    RustlsTls(StreamOwned<ClientConnection, TcpStream>),
+    Rustls(StreamOwned<ClientConnection, TcpStream>),
     #[cfg(feature = "boring-tls")]
     BoringTls(SslStream<TcpStream>),
     /// Can't be built
@@ -60,7 +60,7 @@ impl NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(s) => s.get_ref().peer_addr(),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(s) => s.get_ref().peer_addr(),
+            InnerNetworkStream::Rustls(s) => s.get_ref().peer_addr(),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(s) => s.get_ref().peer_addr(),
             InnerNetworkStream::None => {
@@ -80,7 +80,7 @@ impl NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(s) => s.get_ref().shutdown(how),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(s) => s.get_ref().shutdown(how),
+            InnerNetworkStream::Rustls(s) => s.get_ref().shutdown(how),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(s) => s.get_ref().shutdown(how),
             InnerNetworkStream::None => {
@@ -174,27 +174,30 @@ impl NetworkStream {
     ) -> Result<InnerNetworkStream, Error> {
         Ok(match &tls_parameters.connector {
             #[cfg(feature = "native-tls")]
-            InnerTlsParameters::NativeTls(connector) => {
+            InnerTlsParameters::NativeTls { connector } => {
                 let stream = connector
                     .connect(tls_parameters.domain(), tcp_stream)
                     .map_err(error::connection)?;
                 InnerNetworkStream::NativeTls(stream)
             }
             #[cfg(feature = "rustls")]
-            InnerTlsParameters::RustlsTls(connector) => {
+            InnerTlsParameters::Rustls { config } => {
                 let domain = ServerName::try_from(tls_parameters.domain())
                     .map_err(|_| error::connection("domain isn't a valid DNS name"))?;
-                let connection = ClientConnection::new(Arc::clone(connector), domain.to_owned())
+                let connection = ClientConnection::new(Arc::clone(config), domain.to_owned())
                     .map_err(error::connection)?;
                 let stream = StreamOwned::new(connection, tcp_stream);
-                InnerNetworkStream::RustlsTls(stream)
+                InnerNetworkStream::Rustls(stream)
             }
             #[cfg(feature = "boring-tls")]
-            InnerTlsParameters::BoringTls(connector) => {
+            InnerTlsParameters::BoringTls {
+                connector,
+                accept_invalid_hostnames,
+            } => {
                 let stream = connector
                     .configure()
                     .map_err(error::connection)?
-                    .verify_hostname(tls_parameters.accept_invalid_hostnames)
+                    .verify_hostname(*accept_invalid_hostnames)
                     .connect(tls_parameters.domain(), tcp_stream)
                     .map_err(error::connection)?;
                 InnerNetworkStream::BoringTls(stream)
@@ -208,7 +211,7 @@ impl NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(_) => true,
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(_) => true,
+            InnerNetworkStream::Rustls(_) => true,
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(_) => true,
             InnerNetworkStream::None => {
@@ -219,13 +222,14 @@ impl NetworkStream {
     }
 
     #[cfg(feature = "boring-tls")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "boring-tls")))]
     pub fn tls_verify_result(&self) -> Result<(), Error> {
         match &self.inner {
             InnerNetworkStream::Tcp(_) => Err(error::client("Connection is not encrypted")),
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(_) => panic!("Unsupported"),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(_) => panic!("Unsupported"),
+            InnerNetworkStream::Rustls(_) => panic!("Unsupported"),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(stream) => {
                 stream.ssl().verify_result().map_err(error::tls)
@@ -235,13 +239,14 @@ impl NetworkStream {
     }
 
     #[cfg(any(feature = "rustls", feature = "boring-tls"))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "rustls", 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")]
-            InnerNetworkStream::RustlsTls(stream) => Ok(stream
+            InnerNetworkStream::Rustls(stream) => Ok(stream
                 .conn
                 .peer_certificates()
                 .unwrap()
@@ -261,6 +266,10 @@ impl NetworkStream {
     }
 
     #[cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+    )]
     pub fn peer_certificate(&self) -> Result<Vec<u8>, Error> {
         match &self.inner {
             InnerNetworkStream::Tcp(_) => Err(error::client("Connection is not encrypted")),
@@ -272,7 +281,7 @@ impl NetworkStream {
                 .to_der()
                 .map_err(error::tls)?),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(stream) => Ok(stream
+            InnerNetworkStream::Rustls(stream) => Ok(stream
                 .conn
                 .peer_certificates()
                 .unwrap()
@@ -296,7 +305,7 @@ impl NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(stream) => stream.get_ref().set_read_timeout(duration),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(stream) => stream.get_ref().set_read_timeout(duration),
+            InnerNetworkStream::Rustls(stream) => stream.get_ref().set_read_timeout(duration),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(stream) => stream.get_ref().set_read_timeout(duration),
             InnerNetworkStream::None => {
@@ -314,7 +323,7 @@ impl NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(stream) => stream.get_ref().set_write_timeout(duration),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(stream) => stream.get_ref().set_write_timeout(duration),
+            InnerNetworkStream::Rustls(stream) => stream.get_ref().set_write_timeout(duration),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(stream) => stream.get_ref().set_write_timeout(duration),
             InnerNetworkStream::None => {
@@ -332,7 +341,7 @@ impl Read for NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(s) => s.read(buf),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(s) => s.read(buf),
+            InnerNetworkStream::Rustls(s) => s.read(buf),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(s) => s.read(buf),
             InnerNetworkStream::None => {
@@ -350,7 +359,7 @@ impl Write for NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(s) => s.write(buf),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(s) => s.write(buf),
+            InnerNetworkStream::Rustls(s) => s.write(buf),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(s) => s.write(buf),
             InnerNetworkStream::None => {
@@ -366,7 +375,7 @@ impl Write for NetworkStream {
             #[cfg(feature = "native-tls")]
             InnerNetworkStream::NativeTls(s) => s.flush(),
             #[cfg(feature = "rustls")]
-            InnerNetworkStream::RustlsTls(s) => s.flush(),
+            InnerNetworkStream::Rustls(s) => s.flush(),
             #[cfg(feature = "boring-tls")]
             InnerNetworkStream::BoringTls(s) => s.flush(),
             InnerNetworkStream::None => {

src/transport/smtp/client/tls.rs

@@ -65,6 +65,16 @@ pub enum TlsVersion {
 /// connecting to a local server.
 #[derive(Clone)]
 #[allow(missing_copy_implementations)]
+#[cfg_attr(
+    not(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")),
+    deprecated(
+        note = "starting from lettre v0.12 `Tls` won't be available when none of the TLS backends are enabled"
+    )
+)]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+)]
 pub enum Tls {
     /// Insecure (plaintext) connection only.
     ///
@@ -138,14 +148,25 @@ impl Debug for Tls {
 /// Source for the base set of root certificates to trust.
 #[allow(missing_copy_implementations)]
 #[derive(Clone, Debug, Default)]
+#[cfg_attr(
+    not(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")),
+    deprecated(
+        note = "starting from lettre v0.12 `CertificateStore` won't be available when none of the TLS backends are enabled"
+    )
+)]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+)]
 pub enum CertificateStore {
     /// Use the default for the TLS backend.
     ///
     /// 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
-    /// enabled, or will fall back to `webpki-roots`.
+    /// For rustls, this will use the system certificate verifier if the `rustls-platform-verifier`
+    /// feature is enabled. If the `rustls-native-certs` feature is enabled, system certificate
+    /// store will be used. Otherwise, it will fall back to `webpki-roots`.
     ///
     /// The boring-tls backend uses the same logic as OpenSSL on all platforms.
     #[default]
@@ -161,16 +182,34 @@ pub enum CertificateStore {
 
 /// Parameters to use for secure clients
 #[derive(Clone)]
+#[cfg_attr(
+    not(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")),
+    deprecated(
+        note = "starting from lettre v0.12 `TlsParameters` won't be available when none of the TLS backends are enabled"
+    )
+)]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+)]
 pub struct TlsParameters {
     pub(crate) connector: InnerTlsParameters,
     /// The domain name which is expected in the TLS certificate from the server
     pub(super) domain: String,
-    #[cfg(feature = "boring-tls")]
-    pub(super) accept_invalid_hostnames: bool,
 }
 
 /// Builder for `TlsParameters`
 #[derive(Debug, Clone)]
+#[cfg_attr(
+    not(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")),
+    deprecated(
+        note = "starting from lettre v0.12 `TlsParametersBuilder` won't be available when none of the TLS backends are enabled"
+    )
+)]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+)]
 pub struct TlsParametersBuilder {
     domain: String,
     cert_store: CertificateStore,
@@ -221,6 +260,8 @@ impl TlsParametersBuilder {
 
     /// Controls whether certificates with an invalid hostname are accepted
     ///
+    /// This option is silently disabled when using `rustls-platform-verifier`.
+    ///
     /// Defaults to `false`.
     ///
     /// # Warning
@@ -244,6 +285,10 @@ impl TlsParametersBuilder {
     ///
     /// Defaults to [`Tlsv12`][TlsVersion::Tlsv12].
     #[cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls"))]
+    #[cfg_attr(
+        docsrs,
+        doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+    )]
     pub fn set_min_tls_version(mut self, min_tls_version: TlsVersion) -> Self {
         self.min_tls_version = min_tls_version;
         self
@@ -328,10 +373,8 @@ impl TlsParametersBuilder {
 
         let connector = tls_builder.build().map_err(error::tls)?;
         Ok(TlsParameters {
-            connector: InnerTlsParameters::NativeTls(connector),
+            connector: InnerTlsParameters::NativeTls { connector },
             domain: self.domain,
-            #[cfg(feature = "boring-tls")]
-            accept_invalid_hostnames: self.accept_invalid_hostnames,
         })
     }
 
@@ -389,9 +432,11 @@ impl TlsParametersBuilder {
             .map_err(error::tls)?;
         let connector = tls_builder.build();
         Ok(TlsParameters {
-            connector: InnerTlsParameters::BoringTls(connector),
+            connector: InnerTlsParameters::BoringTls {
+                connector,
+                accept_invalid_hostnames: self.accept_invalid_hostnames,
+            },
             domain: self.domain,
-            accept_invalid_hostnames: self.accept_invalid_hostnames,
         })
     }
 
@@ -419,7 +464,10 @@ impl TlsParametersBuilder {
         // Build TLS config
         let mut root_cert_store = RootCertStore::empty();
 
-        #[cfg(feature = "rustls-native-certs")]
+        #[cfg(all(
+            not(feature = "rustls-platform-verifier"),
+            feature = "rustls-native-certs"
+        ))]
         fn load_native_roots(store: &mut RootCertStore) {
             let rustls_native_certs::CertificateResult { certs, errors, .. } =
                 rustls_native_certs::load_native_certs();
@@ -439,11 +487,26 @@ impl TlsParametersBuilder {
             store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
         }
 
+        #[cfg_attr(not(feature = "rustls-platform-verifier"), allow(unused_mut))]
+        let mut extra_roots = None::<Vec<CertificateDer<'static>>>;
         match self.cert_store {
             CertificateStore::Default => {
-                #[cfg(feature = "rustls-native-certs")]
+                #[cfg(feature = "rustls-platform-verifier")]
+                {
+                    extra_roots = Some(Vec::new());
+                }
+
+                #[cfg(all(
+                    not(feature = "rustls-platform-verifier"),
+                    feature = "rustls-native-certs"
+                ))]
                 load_native_roots(&mut root_cert_store);
-                #[cfg(all(not(feature = "rustls-native-certs"), feature = "webpki-roots"))]
+
+                #[cfg(all(
+                    not(feature = "rustls-platform-verifier"),
+                    not(feature = "rustls-native-certs"),
+                    feature = "webpki-roots"
+                ))]
                 load_webpki_roots(&mut root_cert_store);
             }
             #[cfg(all(feature = "rustls", feature = "webpki-roots"))]
@@ -454,11 +517,17 @@ impl TlsParametersBuilder {
         }
         for cert in self.root_certs {
             for rustls_cert in cert.rustls {
+                #[cfg(feature = "rustls-platform-verifier")]
+                if let Some(extra_roots) = &mut extra_roots {
+                    extra_roots.push(rustls_cert.clone());
+                }
                 root_cert_store.add(rustls_cert).map_err(error::tls)?;
             }
         }
 
-        let tls = if self.accept_invalid_certs || self.accept_invalid_hostnames {
+        let tls = if self.accept_invalid_certs
+            || (extra_roots.is_none() && self.accept_invalid_hostnames)
+        {
             let verifier = InvalidCertsVerifier {
                 ignore_invalid_hostnames: self.accept_invalid_hostnames,
                 ignore_invalid_certs: self.accept_invalid_certs,
@@ -468,7 +537,23 @@ impl TlsParametersBuilder {
             tls.dangerous()
                 .with_custom_certificate_verifier(Arc::new(verifier))
         } else {
-            tls.with_root_certificates(root_cert_store)
+            #[cfg(feature = "rustls-platform-verifier")]
+            if let Some(extra_roots) = extra_roots {
+                tls.dangerous().with_custom_certificate_verifier(Arc::new(
+                    rustls_platform_verifier::Verifier::new_with_extra_roots(
+                        extra_roots,
+                        crypto_provider,
+                    )
+                    .map_err(error::tls)?,
+                ))
+            } else {
+                tls.with_root_certificates(root_cert_store)
+            }
+
+            #[cfg(not(feature = "rustls-platform-verifier"))]
+            {
+                tls.with_root_certificates(root_cert_store)
+            }
         };
 
         let tls = if let Some(identity) = self.identity {
@@ -480,10 +565,10 @@ impl TlsParametersBuilder {
         };
 
         Ok(TlsParameters {
-            connector: InnerTlsParameters::RustlsTls(Arc::new(tls)),
+            connector: InnerTlsParameters::Rustls {
+                config: Arc::new(tls),
+            },
             domain: self.domain,
-            #[cfg(feature = "boring-tls")]
-            accept_invalid_hostnames: self.accept_invalid_hostnames,
         })
     }
 }
@@ -492,11 +577,14 @@ impl TlsParametersBuilder {
 #[allow(clippy::enum_variant_names)]
 pub(crate) enum InnerTlsParameters {
     #[cfg(feature = "native-tls")]
-    NativeTls(TlsConnector),
+    NativeTls { connector: TlsConnector },
     #[cfg(feature = "rustls")]
-    RustlsTls(Arc<ClientConfig>),
+    Rustls { config: Arc<ClientConfig> },
     #[cfg(feature = "boring-tls")]
-    BoringTls(SslConnector),
+    BoringTls {
+        connector: SslConnector,
+        accept_invalid_hostnames: bool,
+    },
 }
 
 impl TlsParameters {
@@ -545,6 +633,16 @@ impl TlsParameters {
 /// A certificate that can be used with [`TlsParametersBuilder::add_root_certificate`]
 #[derive(Clone)]
 #[allow(missing_copy_implementations)]
+#[cfg_attr(
+    not(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")),
+    deprecated(
+        note = "starting from lettre v0.12 `Certificate` won't be available when none of the TLS backends are enabled"
+    )
+)]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+)]
 pub struct Certificate {
     #[cfg(feature = "native-tls")]
     native_tls: native_tls::Certificate,
@@ -608,6 +706,16 @@ impl Debug for Certificate {
 
 /// An identity that can be used with [`TlsParametersBuilder::identify_with`]
 #[allow(missing_copy_implementations)]
+#[cfg_attr(
+    not(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")),
+    deprecated(
+        note = "starting from lettre v0.12 `Identity` won't be available when none of the TLS backends are enabled"
+    )
+)]
+#[cfg_attr(
+    docsrs,
+    doc(cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls")))
+)]
 pub struct Identity {
     #[cfg(feature = "native-tls")]
     native_tls: native_tls::Identity,

src/transport/smtp/connection_url.rs

@@ -13,6 +13,7 @@ use super::{
 
 pub(crate) trait TransportBuilder {
     fn new<T: Into<String>>(server: T) -> Self;
+    #[cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls"))]
     fn tls(self, tls: super::Tls) -> Self;
     fn port(self, port: u16) -> Self;
     fn credentials(self, credentials: Credentials) -> Self;
@@ -24,6 +25,7 @@ impl TransportBuilder for SmtpTransportBuilder {
         Self::new(server)
     }
 
+    #[cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls"))]
     fn tls(self, tls: super::Tls) -> Self {
         self.tls(tls)
     }
@@ -47,6 +49,7 @@ impl TransportBuilder for AsyncSmtpTransportBuilder {
         Self::new(server)
     }
 
+    #[cfg(any(feature = "native-tls", feature = "rustls", feature = "boring-tls"))]
     fn tls(self, tls: super::Tls) -> Self {
         self.tls(tls)
     }

src/transport/smtp/pool/async_impl.rs

@@ -149,11 +149,7 @@ impl<E: Executor> Pool<E> {
     pub(crate) async fn shutdown(&self) {
         let connections = { self.connections.lock().await.take() };
         if let Some(connections) = connections {
-            stream::iter(connections)
-                .for_each_concurrent(8, |conn| async move {
-                    conn.unpark().abort().await;
-                })
-                .await;
+            abort_concurrent(connections.into_iter().map(ParkedConnection::unpark)).await;
         }
 
         if let Some(handle) = self.handle.get() {

src/transport/smtp/transport.rs

@@ -177,7 +177,7 @@ impl SmtpTransport {
     /// a proper URL encoder, like the following cargo script:
     ///
     /// ```rust
-    /// # let _ = r#"
+    /// # const TOML: &str = r#"
     /// #!/usr/bin/env cargo
     ///
     /// //! ```cargo

src/transport/stub/mod.rs

@@ -43,13 +43,11 @@
 use std::{
     error::Error as StdError,
     fmt,
-    sync::{Arc, Mutex as StdMutex},
+    sync::{Arc, Mutex},
 };
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 use async_trait::async_trait;
-#[cfg(any(feature = "tokio1", feature = "async-std1"))]
-use futures_util::lock::Mutex as FuturesMutex;
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 use crate::AsyncTransport;
@@ -72,7 +70,7 @@ impl StdError for Error {}
 #[derive(Debug, Clone)]
 pub struct StubTransport {
     response: Result<(), Error>,
-    message_log: Arc<StdMutex<Vec<(Envelope, String)>>>,
+    message_log: Arc<Mutex<Vec<(Envelope, String)>>>,
 }
 
 /// This transport logs messages and always returns the given response
@@ -81,7 +79,7 @@ pub struct StubTransport {
 #[cfg_attr(docsrs, doc(cfg(any(feature = "tokio1", feature = "async-std1"))))]
 pub struct AsyncStubTransport {
     response: Result<(), Error>,
-    message_log: Arc<FuturesMutex<Vec<(Envelope, String)>>>,
+    message_log: Arc<Mutex<Vec<(Envelope, String)>>>,
 }
 
 impl StubTransport {
@@ -89,7 +87,7 @@ impl StubTransport {
     pub fn new(response: Result<(), Error>) -> Self {
         Self {
             response,
-            message_log: Arc::new(StdMutex::new(vec![])),
+            message_log: Arc::new(Mutex::new(vec![])),
         }
     }
 
@@ -97,7 +95,7 @@ impl StubTransport {
     pub fn new_ok() -> Self {
         Self {
             response: Ok(()),
-            message_log: Arc::new(StdMutex::new(vec![])),
+            message_log: Arc::new(Mutex::new(vec![])),
         }
     }
 
@@ -105,7 +103,7 @@ impl StubTransport {
     pub fn new_error() -> Self {
         Self {
             response: Err(Error),
-            message_log: Arc::new(StdMutex::new(vec![])),
+            message_log: Arc::new(Mutex::new(vec![])),
         }
     }
 
@@ -124,7 +122,7 @@ impl AsyncStubTransport {
     pub fn new(response: Result<(), Error>) -> Self {
         Self {
             response,
-            message_log: Arc::new(FuturesMutex::new(vec![])),
+            message_log: Arc::new(Mutex::new(vec![])),
         }
     }
 
@@ -132,7 +130,7 @@ impl AsyncStubTransport {
     pub fn new_ok() -> Self {
         Self {
             response: Ok(()),
-            message_log: Arc::new(FuturesMutex::new(vec![])),
+            message_log: Arc::new(Mutex::new(vec![])),
         }
     }
 
@@ -140,14 +138,14 @@ impl AsyncStubTransport {
     pub fn new_error() -> Self {
         Self {
             response: Err(Error),
-            message_log: Arc::new(FuturesMutex::new(vec![])),
+            message_log: Arc::new(Mutex::new(vec![])),
         }
     }
 
     /// Return all logged messages sent using [`AsyncTransport::send_raw`]
     #[cfg(any(feature = "tokio1", feature = "async-std1"))]
     pub async fn messages(&self) -> Vec<(Envelope, String)> {
-        self.message_log.lock().await.clone()
+        self.message_log.lock().unwrap().clone()
     }
 }
 
@@ -173,7 +171,7 @@ impl AsyncTransport for AsyncStubTransport {
     async fn send_raw(&self, envelope: &Envelope, email: &[u8]) -> Result<Self::Ok, Self::Error> {
         self.message_log
             .lock()
-            .await
+            .unwrap()
             .push((envelope.clone(), String::from_utf8_lossy(email).into()));
         self.response
     }