Prepare v0.11.10 (#1002)

CHANGELOG.md

@@ -1,3 +1,14 @@
+<a name="v0.11.10"></a>
+### v0.11.10 (2024-10-23)
+
+#### Bug fixes
+
+* Ignore disconnect errors when `pool` feature of SMTP transport is disabled ([#999])
+* Use case insensitive comparisons for matching login challenge requests ([#1000])
+
+[#999]: https://github.com/lettre/lettre/pull/999
+[#1000]: https://github.com/lettre/lettre/pull/1000
+
 <a name="v0.11.9"></a>
 ### v0.11.9 (2024-09-13)
 

Cargo.lock

@@ -1178,7 +1178,7 @@ checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
 
 [[package]]
 name = "lettre"
-version = "0.11.9"
+version = "0.11.10"
 dependencies = [
  "async-std",
  "async-trait",

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 = "0.11.10"
 description = "Email client"
 readme = "README.md"
 homepage = "https://lettre.rs"

README.md

@@ -28,8 +28,8 @@
 </div>
 
 <div align="center">
-  <a href="https://deps.rs/crate/lettre/0.11.9">
+  <a href="https://deps.rs/crate/lettre/0.11.10">
-    <img src="https://deps.rs/crate/lettre/0.11.9/status.svg"
+    <img src="https://deps.rs/crate/lettre/0.11.10/status.svg"
       alt="dependency status" />
   </a>
 </div>

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/0.11.10")]
 #![doc(html_favicon_url = "https://lettre.rs/favicon.ico")]
 #![doc(html_logo_url = "https://avatars0.githubusercontent.com/u/15113230?v=4")]
 #![forbid(unsafe_code)]

src/transport/smtp/async_transport.rs

@@ -45,7 +45,7 @@ impl AsyncTransport for AsyncSmtpTransport<Tokio1Executor> {
         let result = conn.send(envelope, email).await?;
 
         #[cfg(not(feature = "pool"))]
-        conn.quit().await?;
+        conn.abort().await;
 
         Ok(result)
     }

src/transport/smtp/authentication.rs

@@ -98,13 +98,17 @@ impl Mechanism {
                 let decoded_challenge = challenge
                     .ok_or_else(|| error::client("This mechanism does expect a challenge"))?;
 
-                if ["User Name", "Username:", "Username", "User Name\0"]
+                if contains_ignore_ascii_case(
-                    .contains(&decoded_challenge)
+                    decoded_challenge,
-                {
+                    ["User Name", "Username:", "Username", "User Name\0"],
+                ) {
                     return Ok(credentials.authentication_identity.clone());
                 }
 
-                if ["Password", "Password:", "Password\0"].contains(&decoded_challenge) {
+                if contains_ignore_ascii_case(
+                    decoded_challenge,
+                    ["Password", "Password:", "Password\0"],
+                ) {
                     return Ok(credentials.secret.clone());
                 }
 
@@ -121,6 +125,15 @@ impl Mechanism {
     }
 }
 
+fn contains_ignore_ascii_case<'a>(
+    haystack: &str,
+    needles: impl IntoIterator<Item = &'a str>,
+) -> bool {
+    needles
+        .into_iter()
+        .any(|item| item.eq_ignore_ascii_case(haystack))
+}
+
 #[cfg(test)]
 mod test {
     use super::{Credentials, Mechanism};
@@ -155,6 +168,23 @@ mod test {
         assert!(mechanism.response(&credentials, None).is_err());
     }
 
+    #[test]
+    fn test_login_case_insensitive() {
+        let mechanism = Mechanism::Login;
+
+        let credentials = Credentials::new("alice".to_owned(), "wonderland".to_owned());
+
+        assert_eq!(
+            mechanism.response(&credentials, Some("username")).unwrap(),
+            "alice"
+        );
+        assert_eq!(
+            mechanism.response(&credentials, Some("password")).unwrap(),
+            "wonderland"
+        );
+        assert!(mechanism.response(&credentials, None).is_err());
+    }
+
     #[test]
     fn test_xoauth2() {
         let mechanism = Mechanism::Xoauth2;

src/transport/smtp/client/async_connection.rs

@@ -10,21 +10,34 @@ use super::{AsyncNetworkStream, ClientCodec, TlsParameters};
 use crate::{
     transport::smtp::{
         authentication::{Credentials, Mechanism},
-        client::{ConnectionState, ConnectionWrapper},
         commands::{Auth, Data, Ehlo, Mail, Noop, Quit, Rcpt, Starttls},
-        error::{self, Error},
+        error,
+        error::Error,
         extension::{ClientId, Extension, MailBodyParameter, MailParameter, ServerInfo},
         response::{parse_response, Response},
     },
     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
-    stream: ConnectionWrapper<BufReader<AsyncNetworkStream>>,
+    /// Value is None before connection
-    /// Whether QUIT has been sent
+    stream: BufReader<AsyncNetworkStream>,
-    sent_quit: bool,
+    /// Panic state
+    panic: bool,
     /// Information about the server
     server_info: ServerInfo,
 }
@@ -112,8 +125,8 @@ impl AsyncSmtpConnection {
     ) -> Result<AsyncSmtpConnection, Error> {
         let stream = BufReader::new(stream);
         let mut conn = AsyncSmtpConnection {
-            stream: ConnectionWrapper::new(stream),
+            stream,
-            sent_quit: false,
+            panic: false,
             server_info: ServerInfo::default(),
         };
         // TODO log
@@ -157,28 +170,30 @@ impl AsyncSmtpConnection {
             mail_options.push(MailParameter::Body(MailBodyParameter::EightBitMime));
         }
 
-        self.command(Mail::new(envelope.from().cloned(), mail_options))
+        try_smtp!(
-            .await?;
+            self.command(Mail::new(envelope.from().cloned(), mail_options))
+                .await,
+            self
+        );
 
         // Recipient
         for to_address in envelope.to() {
-            self.command(Rcpt::new(to_address.clone(), vec![])).await?;
+            try_smtp!(
+                self.command(Rcpt::new(to_address.clone(), vec![])).await,
+                self
+            );
         }
 
         // Data
-        self.command(Data).await?;
+        try_smtp!(self.command(Data).await, self);
 
         // Message content
-        let result = self.message(email).await?;
+        let result = try_smtp!(self.message(email).await, self);
         Ok(result)
     }
 
     pub fn has_broken(&self) -> bool {
-        self.sent_quit
+        self.panic
-            || matches!(
-                self.stream.state(),
-                ConnectionState::BrokenConnection | ConnectionState::BrokenResponse
-            )
     }
 
     pub fn can_starttls(&self) -> bool {
@@ -198,14 +213,12 @@ impl AsyncSmtpConnection {
         hello_name: &ClientId,
     ) -> Result<(), Error> {
         if self.server_info.supports_feature(Extension::StartTls) {
-            self.command(Starttls).await?;
+            try_smtp!(self.command(Starttls).await, self);
-            self.stream
+            self.stream.get_mut().upgrade_tls(tls_parameters).await?;
-                .async_op(|stream| stream.get_mut().upgrade_tls(tls_parameters))
-                .await?;
             #[cfg(feature = "tracing")]
             tracing::debug!("connection encrypted");
             // Send EHLO again
-            self.ehlo(hello_name).await?;
+            try_smtp!(self.ehlo(hello_name).await, self);
             Ok(())
         } else {
             Err(error::client("STARTTLS is not supported on this server"))
@@ -214,39 +227,32 @@ impl AsyncSmtpConnection {
 
     /// Send EHLO and update server info
     async fn ehlo(&mut self, hello_name: &ClientId) -> Result<(), Error> {
-        let ehlo_response = self.command(Ehlo::new(hello_name.clone())).await?;
+        let ehlo_response = try_smtp!(self.command(Ehlo::new(hello_name.clone())).await, self);
-        self.server_info = ServerInfo::from_response(&ehlo_response)?;
+        self.server_info = try_smtp!(ServerInfo::from_response(&ehlo_response), self);
         Ok(())
     }
 
     pub async fn quit(&mut self) -> Result<Response, Error> {
-        self.sent_quit = true;
+        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
-        // `write` already rejects writes if the connection state if bad
+        if !self.panic {
-        if !self.sent_quit {
+            self.panic = true;
-            let _ = self.quit().await;
+            let _ = self.command(Quit).await;
-        }
-
-        if !matches!(self.stream.state(), ConnectionState::BrokenConnection) {
-            let _ = self
-                .stream
-                .async_op(|stream| async { stream.close().await.map_err(error::network) })
-                .await;
         }
+        let _ = self.stream.close().await;
     }
 
     /// Sets the underlying stream
     pub fn set_stream(&mut self, stream: AsyncNetworkStream) {
-        self.stream = ConnectionWrapper::new(BufReader::new(stream));
+        self.stream = BufReader::new(stream);
     }
 
     /// Tells if the underlying stream is currently encrypted
     pub fn is_encrypted(&self) -> bool {
-        self.stream.get_ref().get_ref().is_encrypted()
+        self.stream.get_ref().is_encrypted()
     }
 
     /// Checks if the server is connected using the NOOP SMTP command
@@ -273,13 +279,15 @@ impl AsyncSmtpConnection {
 
         while challenges > 0 && response.has_code(334) {
             challenges -= 1;
-            response = self
+            response = try_smtp!(
-                .command(Auth::new_from_response(
+                self.command(Auth::new_from_response(
                     mechanism,
                     credentials.clone(),
                     &response,
                 )?)
-                .await?;
+                .await,
+                self
+            );
         }
 
         if challenges == 0 {
@@ -308,17 +316,15 @@ impl AsyncSmtpConnection {
     /// Writes a string to the server
     async fn write(&mut self, string: &[u8]) -> Result<(), Error> {
         self.stream
-            .async_op(|stream| async {
+            .get_mut()
-                stream
+            .write_all(string)
-                    .get_mut()
+            .await
-                    .write_all(string)
+            .map_err(error::network)?;
-                    .await
-                    .map_err(error::network)
-            })
-            .await?;
         self.stream
-            .async_op(|stream| async { stream.get_mut().flush().await.map_err(error::network) })
+            .get_mut()
-            .await?;
+            .flush()
+            .await
+            .map_err(error::network)?;
 
         #[cfg(feature = "tracing")]
         tracing::debug!("Wrote: {}", escape_crlf(&String::from_utf8_lossy(string)));
@@ -331,10 +337,9 @@ impl AsyncSmtpConnection {
 
         while self
             .stream
-            .async_op(|stream| async {
+            .read_line(&mut buffer)
-                stream.read_line(&mut buffer).await.map_err(error::network)
+            .await
-            })
+            .map_err(error::network)?
-            .await?
             > 0
         {
             #[cfg(feature = "tracing")]
@@ -351,12 +356,10 @@ impl AsyncSmtpConnection {
                     }
                 }
                 Err(nom::Err::Failure(e)) => {
-                    self.stream.set_state(ConnectionState::BrokenResponse);
                     return Err(error::response(e.to_string()));
                 }
                 Err(nom::Err::Incomplete(_)) => { /* read more */ }
                 Err(nom::Err::Error(e)) => {
-                    self.stream.set_state(ConnectionState::BrokenResponse);
                     return Err(error::response(e.to_string()));
                 }
             }
@@ -368,12 +371,12 @@ impl AsyncSmtpConnection {
     /// The X509 certificate of the server (DER encoded)
     #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
     pub fn peer_certificate(&self) -> Result<Vec<u8>, Error> {
-        self.stream.get_ref().get_ref().peer_certificate()
+        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().get_ref().certificate_chain()
+        self.stream.get_ref().certificate_chain()
     }
 }

src/transport/smtp/client/connection.rs

@@ -7,25 +7,38 @@ use std::{
 
 #[cfg(feature = "tracing")]
 use super::escape_crlf;
-use super::{ClientCodec, ConnectionWrapper, NetworkStream, TlsParameters};
+use super::{ClientCodec, NetworkStream, TlsParameters};
 use crate::{
     address::Envelope,
     transport::smtp::{
         authentication::{Credentials, Mechanism},
-        client::ConnectionState,
         commands::{Auth, Data, Ehlo, Mail, Noop, Quit, Rcpt, Starttls},
-        error::{self, Error},
+        error,
+        error::Error,
         extension::{ClientId, Extension, MailBodyParameter, MailParameter, ServerInfo},
         response::{parse_response, Response},
     },
 };
 
+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
-    stream: ConnectionWrapper<BufReader<NetworkStream>>,
+    /// Value is None before connection
-    /// Whether QUIT has been sent
+    stream: BufReader<NetworkStream>,
-    sent_quit: bool,
+    /// Panic state
+    panic: bool,
     /// Information about the server
     server_info: ServerInfo,
 }
@@ -51,8 +64,8 @@ impl SmtpConnection {
         let stream = NetworkStream::connect(server, timeout, tls_parameters, local_address)?;
         let stream = BufReader::new(stream);
         let mut conn = SmtpConnection {
-            stream: ConnectionWrapper::new(stream),
+            stream,
-            sent_quit: false,
+            panic: false,
             server_info: ServerInfo::default(),
         };
         conn.set_timeout(timeout).map_err(error::network)?;
@@ -97,27 +110,26 @@ impl SmtpConnection {
             mail_options.push(MailParameter::Body(MailBodyParameter::EightBitMime));
         }
 
-        self.command(Mail::new(envelope.from().cloned(), mail_options))?;
+        try_smtp!(
+            self.command(Mail::new(envelope.from().cloned(), mail_options)),
+            self
+        );
 
         // Recipient
         for to_address in envelope.to() {
-            self.command(Rcpt::new(to_address.clone(), vec![]))?;
+            try_smtp!(self.command(Rcpt::new(to_address.clone(), vec![])), self);
         }
 
         // Data
-        self.command(Data)?;
+        try_smtp!(self.command(Data), self);
 
         // Message content
-        let result = self.message(email)?;
+        let result = try_smtp!(self.message(email), self);
         Ok(result)
     }
 
     pub fn has_broken(&self) -> bool {
-        self.sent_quit
+        self.panic
-            || matches!(
-                self.stream.state(),
-                ConnectionState::BrokenConnection | ConnectionState::BrokenResponse
-            )
     }
 
     pub fn can_starttls(&self) -> bool {
@@ -133,13 +145,12 @@ impl SmtpConnection {
         if self.server_info.supports_feature(Extension::StartTls) {
             #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
             {
-                self.command(Starttls)?;
+                try_smtp!(self.command(Starttls), self);
-                self.stream
+                self.stream.get_mut().upgrade_tls(tls_parameters)?;
-                    .sync_op(|stream| stream.get_mut().upgrade_tls(tls_parameters))?;
                 #[cfg(feature = "tracing")]
                 tracing::debug!("connection encrypted");
                 // Send EHLO again
-                self.ehlo(hello_name)?;
+                try_smtp!(self.ehlo(hello_name), self);
                 Ok(())
             }
             #[cfg(not(any(
@@ -157,47 +168,38 @@ impl SmtpConnection {
 
     /// Send EHLO and update server info
     fn ehlo(&mut self, hello_name: &ClientId) -> Result<(), Error> {
-        let ehlo_response = self.command(Ehlo::new(hello_name.clone()))?;
+        let ehlo_response = try_smtp!(self.command(Ehlo::new(hello_name.clone())), self);
-        self.server_info = ServerInfo::from_response(&ehlo_response)?;
+        self.server_info = try_smtp!(ServerInfo::from_response(&ehlo_response), self);
         Ok(())
     }
 
     pub fn quit(&mut self) -> Result<Response, Error> {
-        self.sent_quit = true;
+        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
-        // `write` already rejects writes if the connection state if bad
+        if !self.panic {
-        if !self.sent_quit {
+            self.panic = true;
-            let _ = self.quit();
+            let _ = self.command(Quit);
-        }
-
-        if !matches!(self.stream.state(), ConnectionState::BrokenConnection) {
-            let _ = self.stream.sync_op(|stream| {
-                stream
-                    .get_mut()
-                    .shutdown(std::net::Shutdown::Both)
-                    .map_err(error::network)
-            });
         }
+        let _ = self.stream.get_mut().shutdown(std::net::Shutdown::Both);
     }
 
     /// Sets the underlying stream
     pub fn set_stream(&mut self, stream: NetworkStream) {
-        self.stream = ConnectionWrapper::new(BufReader::new(stream));
+        self.stream = BufReader::new(stream);
     }
 
     /// Tells if the underlying stream is currently encrypted
     pub fn is_encrypted(&self) -> bool {
-        self.stream.get_ref().get_ref().is_encrypted()
+        self.stream.get_ref().is_encrypted()
     }
 
     /// Set timeout
     pub fn set_timeout(&mut self, duration: Option<Duration>) -> io::Result<()> {
-        self.stream.get_mut().get_mut().set_read_timeout(duration)?;
+        self.stream.get_mut().set_read_timeout(duration)?;
-        self.stream.get_mut().get_mut().set_write_timeout(duration)
+        self.stream.get_mut().set_write_timeout(duration)
     }
 
     /// Checks if the server is connected using the NOOP SMTP command
@@ -222,11 +224,14 @@ impl SmtpConnection {
 
         while challenges > 0 && response.has_code(334) {
             challenges -= 1;
-            response = self.command(Auth::new_from_response(
+            response = try_smtp!(
-                mechanism,
+                self.command(Auth::new_from_response(
-                credentials.clone(),
+                    mechanism,
-                &response,
+                    credentials.clone(),
-            )?)?;
+                    &response,
+                )?),
+                self
+            );
         }
 
         if challenges == 0 {
@@ -256,9 +261,10 @@ impl SmtpConnection {
     /// Writes a string to the server
     fn write(&mut self, string: &[u8]) -> Result<(), Error> {
         self.stream
-            .sync_op(|stream| stream.get_mut().write_all(string).map_err(error::network))?;
+            .get_mut()
-        self.stream
+            .write_all(string)
-            .sync_op(|stream| stream.get_mut().flush().map_err(error::network))?;
+            .map_err(error::network)?;
+        self.stream.get_mut().flush().map_err(error::network)?;
 
         #[cfg(feature = "tracing")]
         tracing::debug!("Wrote: {}", escape_crlf(&String::from_utf8_lossy(string)));
@@ -269,11 +275,7 @@ impl SmtpConnection {
     pub fn read_response(&mut self) -> Result<Response, Error> {
         let mut buffer = String::with_capacity(100);
 
-        while self
+        while self.stream.read_line(&mut buffer).map_err(error::network)? > 0 {
-            .stream
-            .sync_op(|stream| stream.read_line(&mut buffer).map_err(error::network))?
-            > 0
-        {
             #[cfg(feature = "tracing")]
             tracing::debug!("<< {}", escape_crlf(&buffer));
             match parse_response(&buffer) {
@@ -288,12 +290,10 @@ impl SmtpConnection {
                     };
                 }
                 Err(nom::Err::Failure(e)) => {
-                    self.stream.set_state(ConnectionState::BrokenResponse);
                     return Err(error::response(e.to_string()));
                 }
                 Err(nom::Err::Incomplete(_)) => { /* read more */ }
                 Err(nom::Err::Error(e)) => {
-                    self.stream.set_state(ConnectionState::BrokenResponse);
                     return Err(error::response(e.to_string()));
                 }
             }
@@ -305,12 +305,12 @@ impl SmtpConnection {
     /// The X509 certificate of the server (DER encoded)
     #[cfg(any(feature = "native-tls", feature = "rustls-tls", feature = "boring-tls"))]
     pub fn peer_certificate(&self) -> Result<Vec<u8>, Error> {
-        self.stream.get_ref().get_ref().peer_certificate()
+        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().get_ref().certificate_chain()
+        self.stream.get_ref().certificate_chain()
     }
 }

src/transport/smtp/client/mod.rs

@@ -24,8 +24,6 @@
 
 #[cfg(feature = "serde")]
 use std::fmt::Debug;
-#[cfg(any(feature = "tokio1", feature = "async-std1"))]
-use std::future::Future;
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 pub use self::async_connection::AsyncSmtpConnection;
@@ -42,7 +40,6 @@ pub use self::{
     connection::SmtpConnection,
     tls::{Certificate, CertificateStore, Identity, Tls, TlsParameters, TlsParametersBuilder},
 };
-use super::{error, Error};
 
 #[cfg(any(feature = "tokio1", feature = "async-std1"))]
 mod async_connection;
@@ -52,99 +49,6 @@ mod connection;
 mod net;
 mod tls;
 
-#[derive(Debug)]
-pub(super) struct ConnectionWrapper<C> {
-    conn: C,
-    state: ConnectionState,
-}
-
-impl<C> ConnectionWrapper<C> {
-    pub(super) fn new(conn: C) -> Self {
-        Self {
-            conn,
-            state: ConnectionState::ProbablyConnected,
-        }
-    }
-
-    pub(super) fn get_ref(&self) -> &C {
-        &self.conn
-    }
-
-    pub(super) fn get_mut(&mut self) -> &mut C {
-        &mut self.conn
-    }
-
-    pub(super) fn state(&self) -> ConnectionState {
-        self.state
-    }
-
-    pub(super) fn set_state(&mut self, state: ConnectionState) {
-        self.state = state;
-    }
-
-    pub(super) fn sync_op<F, T>(&mut self, f: F) -> Result<T, Error>
-    where
-        F: FnOnce(&mut C) -> Result<T, Error>,
-    {
-        if !matches!(
-            self.state,
-            ConnectionState::ProbablyConnected | ConnectionState::BrokenResponse
-        ) {
-            return Err(error::client(
-                "attempted to send operation to broken connection",
-            ));
-        }
-
-        self.state = ConnectionState::Writing;
-        match f(&mut self.conn) {
-            Ok(t) => {
-                self.state = ConnectionState::ProbablyConnected;
-                Ok(t)
-            }
-            Err(err) => {
-                self.state = ConnectionState::BrokenConnection;
-                Err(err)
-            }
-        }
-    }
-
-    #[cfg(any(feature = "tokio1", feature = "async-std1"))]
-    pub(super) async fn async_op<'a, F, Fut, T>(&'a mut self, f: F) -> Result<T, Error>
-    where
-        F: FnOnce(&'a mut C) -> Fut,
-        Fut: Future<Output = Result<T, Error>>,
-    {
-        if !matches!(
-            self.state,
-            ConnectionState::ProbablyConnected | ConnectionState::BrokenResponse
-        ) {
-            return Err(error::client(
-                "attempted to send operation to broken connection",
-            ));
-        }
-
-        self.state = ConnectionState::Writing;
-        match f(&mut self.conn).await {
-            Ok(t) => {
-                self.state = ConnectionState::ProbablyConnected;
-                Ok(t)
-            }
-            Err(err) => {
-                self.state = ConnectionState::BrokenConnection;
-                Err(err)
-            }
-        }
-    }
-}
-
-#[derive(Debug, Copy, Clone)]
-pub(super) enum ConnectionState {
-    ProbablyConnected,
-    Writing,
-    BrokenResponse,
-    BrokenConnection,
-}
-
 /// The codec used for transparency
 #[derive(Debug)]
 struct ClientCodec {

src/transport/smtp/transport.rs

@@ -32,7 +32,7 @@ impl Transport for SmtpTransport {
         let result = conn.send(envelope, email)?;
 
         #[cfg(not(feature = "pool"))]
-        conn.quit()?;
+        conn.abort();
 
         Ok(result)
     }