fix(builder): lettre_email 0.9.4

Mention SmtpClient::new_simple in the docs for SmtpClient::new

.build-scripts/site-upload.sh

@@ -4,7 +4,7 @@ set -xe
 
 cd website
 make clean && make
-echo "lettre.at" > _book/CNAME
+echo "lettre.at" > _book/html/CNAME
 sudo pip install ghp-import
-ghp-import -n _book
-git push -f https://${GH_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git gh-pages
+ghp-import -n _book/html
+git push -f https://${GH_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git gh-pages

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -0,0 +1,21 @@
+---
+name: Bug report
+about: Create a report to help us improve
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Code allowing to reproduce the bug.
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Environment (please complete the following information):**
+- Lettre version
+- OS
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/Feature_request.md

@@ -0,0 +1,17 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.travis.yml

@@ -3,7 +3,7 @@ rust:
 - stable
 - beta
 - nightly
-- 1.20.0
+- 1.32.0
 matrix:
   allow_failures:
   - rust: nightly
@@ -19,13 +19,11 @@ addons:
     - gcc
     - binutils-dev
     - libiberty-dev
-    - npm
 before_script:
 - smtp-sink 2525 1000&
 - sudo chgrp -R postdrop /var/spool/postfix/maildrop
-- sudo npm set strict-ssl false && sudo npm install -g gitbook-cli
 script:
-- cargo test --verbose --all
+- cargo test --verbose --all --all-features
 after_success:
 - ./.build-scripts/codecov.sh
-- '[ "$TRAVIS_BRANCH" = "v0.8.x" ] && [ $TRAVIS_PULL_REQUEST = false ] && ./.build-scripts/site-upload.sh'
+- '[ "$TRAVIS_RUST_VERSION" = "stable" ] && [ "$TRAVIS_BRANCH" = "v0.9.x" ] && [ $TRAVIS_PULL_REQUEST = false ] && ./.build-scripts/site-upload.sh'

CHANGELOG.md

@@ -1,3 +1,69 @@
+<a name="v0.9.4"></a>
+### v0.9.4 (2020-04-21)
+
+#### Bug Fixes
+
+* **email**
+  * Go back to `rust-email` 0.0.20 as upgrade broke message formatting ([6a40f4a](https://github.com/lettre/lettre/commit/6a40f4a)
+
+<a name="v0.9.3"></a>
+### v0.9.3 (2020-04-19)
+
+#### Bug Fixes
+
+* **all:**
+  * Fix compilation warnings ([9b591ff](https://github.com/lettre/lettre/commit/9b591ff932e35947f793aaaeec0e3f06e8818449))
+
+* **email**
+  * Update `rust-email` to 0.0.21 ([eff4e169](https://github.com/lettre/lettre/commit/eff4e1693f5e65430b851707fdfd18046bc796e3))
+
+<a name="v0.9.2"></a>
+### v0.9.2 (2019-06-11)
+
+#### Bug Fixes
+
+* **email:**
+  * Fix compilation with Rust 1.36+ ([393ef8d](https://github.com/lettre/lettre/commit/393ef8dcd1b1c6a6119d0666d5f09b12f50f6b4b))
+
+<a name="v0.9.1"></a>
+### v0.9.1 (2019-05-05)
+
+#### Features
+
+* **email:**
+  * Re-export mime crate ([a0c8fb9](https://github.com/lettre/lettre/commit/a0c8fb9))
+
+<a name="v0.9.0"></a>
+### v0.9.0 (2019-03-17)
+
+#### Bug Fixes
+
+* **email:**
+  * Inserting 'from' from envelope into message headers ([058fa69](https://github.com/lettre/lettre/commit/058fa69))
+  * Do not include Bcc addresses in headers ([ee31bbe](https://github.com/lettre/lettre/commit/ee31bbe))
+
+* **transport:**
+  * Write timeout is not set in smtp transport ([d71b560](https://github.com/lettre/lettre/commit/d71b560))
+  * Client::read_response infinite loop ([72f3cd8](https://github.com/lettre/lettre/commit/72f3cd8))
+
+#### Features
+
+* **all:**
+  * Update dependencies
+  * Start using the failure crate for errors ([c10fe3d](https://github.com/lettre/lettre/commit/c10fe3d))
+
+* **transport:**
+  * Remove TLS 1.1 in accepted protocols by default (only allow TLS 1.2) ([4b48bdb](https://github.com/lettre/lettre/commit/4b48bdb))
+  * Initial support for XOAUTH2 ([ed7c164](https://github.com/lettre/lettre/commit/ed7c164))
+  * Remove support for CRAM-MD5 ([bc09aa2](https://github.com/lettre/lettre/commit/bc09aa2))
+  * SMTP connection pool implementation with r2d2 ([434654e](https://github.com/lettre/lettre/commit/434654e))
+  * Use md-5 and hmac instead of rust-crypto ([e7e0f34](https://github.com/lettre/lettre/commit/e7e0f34))
+  * Gmail transport simple example ([a8d8e2a](https://github.com/lettre/lettre/commit/a8d8e2a))
+
+* **email:**
+  * Add In-Reply-To and References headers ([fc91bb6](https://github.com/lettre/lettre/commit/fc91bb6))
+  * Remove non-chaining builder methods ([1baf8a9](https://github.com/lettre/lettre/commit/1baf8a9))
+
 <a name="v0.8.2"></a>
 ### v0.8.2 (2018-05-03)
 

README.md

@@ -34,19 +34,18 @@ Lettre provides the following features:
 
 ## Example
 
-This library requires Rust 1.20 or newer.
+This library requires Rust 1.32 or newer.
 To use this library, add the following to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-lettre = "0.8"
-lettre_email = "0.8"
+lettre = "0.9"
+lettre_email = "0.9"
 ```
 
 ```rust,no_run
 extern crate lettre;
 extern crate lettre_email;
-extern crate mime;
 
 use lettre::{EmailTransport, SmtpTransport};
 use lettre_email::EmailBuilder;
@@ -60,7 +59,6 @@ fn main() {
         .from("user@example.com")
         .subject("Hi, Hello world")
         .text("Hello world.")
-        .attachment(Path::new("Cargo.toml"), None, &mime::TEXT_PLAIN).unwrap()
         .build()
         .unwrap();
 

lettre/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "lettre"
-version = "0.8.2" # remember to update html_root_url
+version = "0.9.3" # remember to update html_root_url
 description = "Email client"
 readme = "README.md"
 homepage = "http://lettre.at"
@@ -20,31 +20,34 @@ is-it-maintained-open-issues = { repository = "lettre/lettre" }
 
 [dependencies]
 log = "^0.4"
-nom = { version = "^3.2", optional = true }
+nom = { version = "^4.0", optional = true }
 bufstream = { version = "^0.1", optional = true }
-native-tls = { version = "^0.1", optional = true }
-base64 = { version = "^0.9", optional = true }
-hex = { version = "^0.3", optional = true }
+native-tls = { version = "^0.2", optional = true }
+base64 = { version = "^0.10", optional = true }
 hostname = { version = "^0.1", optional = true }
-md-5 = { version = "^0.7", optional = true }
-hmac = { version = "^0.6", optional = true }
 serde = { version = "^1.0", optional = true }
 serde_json = { version = "^1.0", optional = true }
 serde_derive = { version = "^1.0", optional = true }
+fast_chemail = "^0.9"
+r2d2 = { version = "^0.8", optional = true}
 
 [dev-dependencies]
-env_logger = "^0.5"
-glob = "0.2"
+env_logger = "^0.6"
+glob = "0.3"
 
 [features]
-default = ["file-transport", "crammd5-auth", "smtp-transport", "sendmail-transport"]
+default = ["file-transport", "smtp-transport", "sendmail-transport"]
 unstable = []
 serde-impls = ["serde", "serde_derive"]
 file-transport = ["serde-impls", "serde_json"]
-crammd5-auth = ["md-5", "hmac", "hex"]
 smtp-transport = ["bufstream", "native-tls", "base64", "nom", "hostname"]
 sendmail-transport = []
+connection-pool = [ "r2d2" ]
 
 [[example]]
 name = "smtp"
 required-features = ["smtp-transport"]
+
+[[example]]
+name = "smtp_gmail"
+required-features = ["smtp-transport"]

lettre/benches/transport_smtp.rs

@@ -3,9 +3,9 @@
 extern crate lettre;
 extern crate test;
 
-use lettre::{ClientSecurity, SmtpTransport};
-use lettre::{EmailAddress, EmailTransport, SimpleSendableEmail};
 use lettre::smtp::ConnectionReuseParameters;
+use lettre::{ClientSecurity, Envelope, SmtpTransport};
+use lettre::{EmailAddress, SendableEmail, Transport};
 
 #[bench]
 fn bench_simple_send(b: &mut test::Bencher) {
@@ -13,13 +13,16 @@ fn bench_simple_send(b: &mut test::Bencher) {
         .unwrap()
         .build();
     b.iter(|| {
-        let email = SimpleSendableEmail::new(
-            EmailAddress::new("user@localhost".to_string()),
-            vec![EmailAddress::new("root@localhost".to_string())],
+        let email = SendableEmail::new(
+            Envelope::new(
+                Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+                vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+            )
+            .unwrap(),
             "id".to_string(),
-            "Hello world".to_string(),
+            "Hello ß☺ example".to_string().into_bytes(),
         );
-        let result = sender.send(&email);
+        let result = sender.send(email);
         assert!(result.is_ok());
     });
 }
@@ -31,13 +34,16 @@ fn bench_reuse_send(b: &mut test::Bencher) {
         .connection_reuse(ConnectionReuseParameters::ReuseUnlimited)
         .build();
     b.iter(|| {
-        let email = SimpleSendableEmail::new(
-            EmailAddress::new("user@localhost".to_string()),
-            vec![EmailAddress::new("root@localhost".to_string())],
+        let email = SendableEmail::new(
+            Envelope::new(
+                Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+                vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+            )
+            .unwrap(),
             "id".to_string(),
-            "Hello world".to_string(),
+            "Hello ß☺ example".to_string().into_bytes(),
         );
-        let result = sender.send(&email);
+        let result = sender.send(email);
         assert!(result.is_ok());
     });
     sender.close()

lettre/examples/smtp.rs

@@ -1,24 +1,25 @@
 extern crate env_logger;
 extern crate lettre;
 
-use lettre::{EmailTransport, SimpleSendableEmail, SmtpTransport};
+use lettre::{EmailAddress, Envelope, SendableEmail, SmtpClient, Transport};
 
 fn main() {
     env_logger::init();
 
-    let email = SimpleSendableEmail::new(
-        "user@localhost".to_string(),
-        &["root@localhost".to_string()],
-        "my-message-id".to_string(),
-        "Hello ß☺ example".to_string(),
-    ).unwrap();
+    let email = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        )
+        .unwrap(),
+        "id".to_string(),
+        "Hello ß☺ example".to_string().into_bytes(),
+    );
 
     // Open a local connection on port 25
-    let mut mailer = SmtpTransport::builder_unencrypted_localhost()
-        .unwrap()
-        .build();
+    let mut mailer = SmtpClient::new_unencrypted_localhost().unwrap().transport();
     // Send the email
-    let result = mailer.send(&email);
+    let result = mailer.send(email);
 
     if result.is_ok() {
         println!("Email sent");

lettre/examples/smtp_gmail.rs

@@ -0,0 +1,38 @@
+extern crate lettre;
+
+use lettre::smtp::authentication::Credentials;
+use lettre::{EmailAddress, Envelope, SendableEmail, SmtpClient, Transport};
+
+fn main() {
+    let email = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("from@gmail.com".to_string()).unwrap()),
+            vec![EmailAddress::new("to@example.com".to_string()).unwrap()],
+        )
+        .unwrap(),
+        "id".to_string(),
+        "Hello example".to_string().into_bytes(),
+    );
+
+    let creds = Credentials::new(
+        "example_username".to_string(),
+        "example_password".to_string(),
+    );
+
+    // Open a remote connection to gmail
+    let mut mailer = SmtpClient::new_simple("smtp.gmail.com")
+        .unwrap()
+        .credentials(creds)
+        .transport();
+
+    // Send the email
+    let result = mailer.send(email);
+
+    if result.is_ok() {
+        println!("Email sent");
+    } else {
+        println!("Could not send email: {:?}", result);
+    }
+
+    assert!(result.is_ok());
+}

lettre/src/error.rs

@@ -0,0 +1,35 @@
+use self::Error::*;
+use std::{
+    error::Error as StdError,
+    fmt::{self, Display, Formatter},
+};
+
+/// Error type for email content
+#[derive(Debug, Clone, Copy)]
+pub enum Error {
+    /// Missing from in envelope
+    MissingFrom,
+    /// Missing to in envelope
+    MissingTo,
+    /// Invalid email
+    InvalidEmailAddress,
+}
+
+impl Display for Error {
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result<(), fmt::Error> {
+        fmt.write_str(&match *self {
+            MissingFrom => "missing source address, invalid envelope".to_owned(),
+            MissingTo => "missing destination address, invalid envelope".to_owned(),
+            InvalidEmailAddress => "invalid email address".to_owned(),
+        })
+    }
+}
+
+impl StdError for Error {
+    fn cause(&self) -> Option<&dyn StdError> {
+        None
+    }
+}
+
+/// Email result type
+pub type EmailResult<T> = Result<T, Error>;

lettre/src/file/error.rs

@@ -2,9 +2,11 @@
 
 use self::Error::*;
 use serde_json;
-use std::error::Error as StdError;
-use std::fmt::{self, Display, Formatter};
 use std::io;
+use std::{
+    error::Error as StdError,
+    fmt::{self, Display, Formatter},
+};
 
 /// An enum of all error kinds.
 #[derive(Debug)]
@@ -19,20 +21,16 @@ pub enum Error {
 
 impl Display for Error {
     fn fmt(&self, fmt: &mut Formatter) -> Result<(), fmt::Error> {
-        fmt.write_str(self.description())
+        match *self {
+            Client(err) => fmt.write_str(err),
+            Io(ref err) => err.fmt(fmt),
+            JsonSerialization(ref err) => err.fmt(fmt),
+        }
     }
 }
 
 impl StdError for Error {
-    fn description(&self) -> &str {
-        match *self {
-            Client(err) => err,
-            Io(ref err) => err.description(),
-            JsonSerialization(ref err) => err.description(),
-        }
-    }
-
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             Io(ref err) => Some(&*err),
             JsonSerialization(ref err) => Some(&*err),
@@ -43,19 +41,19 @@ impl StdError for Error {
 
 impl From<io::Error> for Error {
     fn from(err: io::Error) -> Error {
-        Io(err)
+        Error::Io(err)
     }
 }
 
 impl From<serde_json::Error> for Error {
     fn from(err: serde_json::Error) -> Error {
-        JsonSerialization(err)
+        Error::JsonSerialization(err)
     }
 }
 
 impl From<&'static str> for Error {
     fn from(string: &'static str) -> Error {
-        Client(string)
+        Error::Client(string)
     }
 }
 

lettre/src/file/mod.rs

@@ -3,52 +3,58 @@
 //! It can be useful for testing purposes, or if you want to keep track of sent messages.
 //!
 
-use EmailTransport;
-use SendableEmail;
-use SimpleSendableEmail;
 use file::error::FileResult;
 use serde_json;
 use std::fs::File;
-use std::io::Read;
 use std::io::prelude::*;
 use std::path::{Path, PathBuf};
+use Envelope;
+use SendableEmail;
+use Transport;
 
 pub mod error;
 
 /// Writes the content and the envelope information to a file
 #[derive(Debug)]
 #[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
-pub struct FileEmailTransport {
+pub struct FileTransport {
     path: PathBuf,
 }
 
-impl FileEmailTransport {
+impl FileTransport {
     /// Creates a new transport to the given directory
-    pub fn new<P: AsRef<Path>>(path: P) -> FileEmailTransport {
-        let mut path_buf = PathBuf::new();
-        path_buf.push(path);
-        FileEmailTransport { path: path_buf }
+    pub fn new<P: AsRef<Path>>(path: P) -> FileTransport {
+        FileTransport {
+            path: PathBuf::from(path.as_ref()),
+        }
     }
 }
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, FileResult> for FileEmailTransport {
-    fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> FileResult {
+#[derive(PartialEq, Eq, Clone, Debug)]
+#[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
+struct SerializableEmail {
+    envelope: Envelope,
+    message_id: String,
+    message: Vec<u8>,
+}
+
+impl<'a> Transport<'a> for FileTransport {
+    type Result = FileResult;
+
+    fn send(&mut self, email: SendableEmail) -> FileResult {
+        let message_id = email.message_id().to_string();
+        let envelope = email.envelope().clone();
+
         let mut file = self.path.clone();
-        file.push(format!("{}.txt", email.message_id()));
+        file.push(format!("{}.json", message_id));
 
-        let mut f = File::create(file.as_path())?;
-
-        let mut message_content = String::new();
-        let _ = email.message().read_to_string(&mut message_content);
-
-        let simple_email = SimpleSendableEmail::new_with_envelope(
-            email.envelope().clone(),
-            email.message_id().to_string(),
-            message_content,
-        );
-
-        f.write_all(serde_json::to_string(&simple_email)?.as_bytes())?;
+        let serialized = serde_json::to_string(&SerializableEmail {
+            envelope,
+            message_id,
+            message: email.message_to_string()?.as_bytes().to_vec(),
+        })?;
 
+        File::create(file.as_path())?.write_all(serialized.as_bytes())?;
         Ok(())
     }
 }

lettre/src/lib.rs

@@ -1,102 +1,80 @@
 //! Lettre is a mailer written in Rust. It provides a simple email builder and several transports.
 //!
-//! This mailer contains the available transports for your emails. To be sendable, the
-//! emails have to implement `SendableEmail`.
+//! This mailer contains the available transports for your emails.
 //!
 
-#![doc(html_root_url = "https://docs.rs/lettre/0.8.2")]
-#![deny(missing_docs, missing_debug_implementations, missing_copy_implementations, trivial_casts,
-        trivial_numeric_casts, unsafe_code, unstable_features, unused_import_braces,
-        unused_qualifications)]
+#![doc(html_root_url = "https://docs.rs/lettre/0.9.3")]
+#![deny(
+    missing_copy_implementations,
+    trivial_casts,
+    trivial_numeric_casts,
+    unsafe_code,
+    unstable_features,
+    unused_import_braces
+)]
 #[cfg(feature = "smtp-transport")]
 extern crate base64;
 #[cfg(feature = "smtp-transport")]
 extern crate bufstream;
-#[cfg(feature = "crammd5-auth")]
-extern crate hex;
-#[cfg(feature = "crammd5-auth")]
-extern crate hmac;
 #[cfg(feature = "smtp-transport")]
 extern crate hostname;
 #[macro_use]
 extern crate log;
-#[cfg(feature = "crammd5-auth")]
-extern crate md5;
 #[cfg(feature = "smtp-transport")]
 extern crate native_tls;
 #[cfg(feature = "smtp-transport")]
 #[macro_use]
 extern crate nom;
 #[cfg(feature = "serde-impls")]
+extern crate serde;
+#[cfg(feature = "serde-impls")]
 #[macro_use]
 extern crate serde_derive;
+extern crate fast_chemail;
+#[cfg(feature = "connection-pool")]
+extern crate r2d2;
 #[cfg(feature = "file-transport")]
 extern crate serde_json;
 
-#[cfg(feature = "smtp-transport")]
-pub mod smtp;
-#[cfg(feature = "sendmail-transport")]
-pub mod sendmail;
-pub mod stub;
+pub mod error;
 #[cfg(feature = "file-transport")]
 pub mod file;
+#[cfg(feature = "sendmail-transport")]
+pub mod sendmail;
+#[cfg(feature = "smtp-transport")]
+pub mod smtp;
+pub mod stub;
 
+use error::EmailResult;
+use error::Error;
+use fast_chemail::is_valid_email;
 #[cfg(feature = "file-transport")]
-pub use file::FileEmailTransport;
+pub use file::FileTransport;
 #[cfg(feature = "sendmail-transport")]
 pub use sendmail::SendmailTransport;
 #[cfg(feature = "smtp-transport")]
-pub use smtp::{ClientSecurity, SmtpTransport};
-#[cfg(feature = "smtp-transport")]
 pub use smtp::client::net::ClientTlsParameters;
+#[cfg(all(feature = "smtp-transport", feature = "connection-pool"))]
+pub use smtp::r2d2::SmtpConnectionManager;
+#[cfg(feature = "smtp-transport")]
+pub use smtp::{ClientSecurity, SmtpClient, SmtpTransport};
+use std::ffi::OsStr;
 use std::fmt::{self, Display, Formatter};
+use std::io;
+use std::io::Cursor;
 use std::io::Read;
-use std::error::Error as StdError;
 use std::str::FromStr;
 
-/// Error type for email content
-#[derive(Debug, Clone, Copy)]
-pub enum Error {
-    /// Missing from in envelope
-    MissingFrom,
-    /// Missing to in envelope
-    MissingTo,
-    /// Invalid email
-    InvalidEmailAddress,
-}
-
-impl StdError for Error {
-    fn description(&self) -> &str {
-        match *self {
-            Error::MissingFrom => "missing source address, invalid envelope",
-            Error::MissingTo => "missing destination address, invalid envelope",
-            Error::InvalidEmailAddress => "invalid email address",
-        }
-    }
-
-    fn cause(&self) -> Option<&StdError> {
-        None
-    }
-}
-
-impl Display for Error {
-    fn fmt(&self, fmt: &mut Formatter) -> Result<(), fmt::Error> {
-        fmt.write_str(self.description())
-    }
-}
-
-/// Email result type
-pub type EmailResult<T> = Result<T, Error>;
-
 /// Email address
 #[derive(PartialEq, Eq, Clone, Debug)]
 #[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
 pub struct EmailAddress(String);
 
 impl EmailAddress {
-    /// Creates a new `EmailAddress`. For now it makes no validation.
     pub fn new(address: String) -> EmailResult<EmailAddress> {
-        // TODO make some basic sanity checks
+        if !is_valid_email(&address) && !address.ends_with("localhost") {
+            return Err(Error::InvalidEmailAddress);
+        }
         Ok(EmailAddress(address))
     }
 }
@@ -115,6 +93,18 @@ impl Display for EmailAddress {
     }
 }
 
+impl AsRef<str> for EmailAddress {
+    fn as_ref(&self) -> &str {
+        &self.0
+    }
+}
+
+impl AsRef<OsStr> for EmailAddress {
+    fn as_ref(&self) -> &OsStr {
+        &self.0.as_ref()
+    }
+}
+
 /// Simple email envelope representation
 ///
 /// We only accept mailboxes, and do not support source routes (as per RFC).
@@ -150,130 +140,74 @@ impl Envelope {
     pub fn from(&self) -> Option<&EmailAddress> {
         self.reverse_path.as_ref()
     }
+}
 
-    /// Creates a new builder
-    pub fn builder() -> EnvelopeBuilder {
-        EnvelopeBuilder::new()
+pub enum Message {
+    Reader(Box<dyn Read + Send>),
+    Bytes(Cursor<Vec<u8>>),
+}
+
+impl Read for Message {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        match *self {
+            Message::Reader(ref mut rdr) => rdr.read(buf),
+            Message::Bytes(ref mut rdr) => rdr.read(buf),
+        }
     }
 }
 
-/// Simple email envelope representation
-#[derive(PartialEq, Eq, Clone, Debug, Default)]
-pub struct EnvelopeBuilder {
-    /// The envelope recipients' addresses
-    to: Vec<EmailAddress>,
-    /// The envelope sender address
-    from: Option<EmailAddress>,
+/// Sendable email structure
+pub struct SendableEmail {
+    envelope: Envelope,
+    message_id: String,
+    message: Message,
 }
 
-impl EnvelopeBuilder {
-    /// Constructs an envelope with no recipients and an empty sender
-    pub fn new() -> Self {
-        EnvelopeBuilder {
-            to: vec![],
-            from: None,
+impl SendableEmail {
+    pub fn new(envelope: Envelope, message_id: String, message: Vec<u8>) -> SendableEmail {
+        SendableEmail {
+            envelope,
+            message_id,
+            message: Message::Bytes(Cursor::new(message)),
         }
     }
 
-    /// Adds a recipient
-    pub fn to<S: Into<EmailAddress>>(mut self, address: S) -> Self {
-        self.add_to(address);
-        self
+    pub fn new_with_reader(
+        envelope: Envelope,
+        message_id: String,
+        message: Box<dyn Read + Send>,
+    ) -> SendableEmail {
+        SendableEmail {
+            envelope,
+            message_id,
+            message: Message::Reader(message),
+        }
     }
 
-    /// Adds a recipient
-    pub fn add_to<S: Into<EmailAddress>>(&mut self, address: S) {
-        self.to.push(address.into());
+    pub fn envelope(&self) -> &Envelope {
+        &self.envelope
     }
 
-    /// Sets the sender
-    pub fn from<S: Into<EmailAddress>>(mut self, address: S) -> Self {
-        self.set_from(address);
-        self
+    pub fn message_id(&self) -> &str {
+        &self.message_id
     }
 
-    /// Sets the sender
-    pub fn set_from<S: Into<EmailAddress>>(&mut self, address: S) {
-        self.from = Some(address.into());
+    pub fn message(self) -> Message {
+        self.message
     }
 
-    /// Build the envelope
-    pub fn build(self) -> EmailResult<Envelope> {
-        Envelope::new(self.from, self.to)
+    pub fn message_to_string(mut self) -> Result<String, io::Error> {
+        let mut message_content = String::new();
+        self.message.read_to_string(&mut message_content)?;
+        Ok(message_content)
     }
 }
 
-/// Email sendable by an SMTP client
-pub trait SendableEmail<'a, T: Read + 'a> {
-    /// Envelope
-    fn envelope(&self) -> Envelope;
-    /// Message ID, used for logging
-    fn message_id(&self) -> String;
-    /// Message content
-    fn message(&'a self) -> Box<T>;
-}
-
 /// Transport method for emails
-pub trait EmailTransport<'a, U: Read + 'a, V> {
+pub trait Transport<'a> {
+    /// Result type for the transport
+    type Result;
+
     /// Sends the email
-    fn send<T: SendableEmail<'a, U> + 'a>(&mut self, email: &'a T) -> V;
-}
-
-/// Minimal email structure
-#[derive(Debug, Clone)]
-#[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
-pub struct SimpleSendableEmail {
-    /// Envelope
-    envelope: Envelope,
-    /// Message ID
-    message_id: String,
-    /// Message content
-    message: Vec<u8>,
-}
-
-impl SimpleSendableEmail {
-    /// Returns a new email
-    pub fn new(
-        from_address: String,
-        to_addresses: &[String],
-        message_id: String,
-        message: String,
-    ) -> EmailResult<SimpleSendableEmail> {
-        let to: Result<Vec<EmailAddress>, Error> = to_addresses
-            .iter()
-            .map(|x| EmailAddress::new(x.clone()))
-            .collect();
-        Ok(SimpleSendableEmail::new_with_envelope(
-            Envelope::new(Some(EmailAddress::new(from_address)?), to?)?,
-            message_id,
-            message,
-        ))
-    }
-
-    /// Returns a new email from a valid envelope
-    pub fn new_with_envelope(
-        envelope: Envelope,
-        message_id: String,
-        message: String,
-    ) -> SimpleSendableEmail {
-        SimpleSendableEmail {
-            envelope,
-            message_id,
-            message: message.into_bytes(),
-        }
-    }
-}
-
-impl<'a> SendableEmail<'a, &'a [u8]> for SimpleSendableEmail {
-    fn envelope(&self) -> Envelope {
-        self.envelope.clone()
-    }
-
-    fn message_id(&self) -> String {
-        self.message_id.clone()
-    }
-
-    fn message(&'a self) -> Box<&[u8]> {
-        Box::new(self.message.as_slice())
-    }
+    fn send(&mut self, email: SendableEmail) -> Self::Result;
 }

lettre/src/sendmail/error.rs

@@ -1,9 +1,11 @@
 //! Error and result type for sendmail transport
 
 use self::Error::*;
-use std::error::Error as StdError;
-use std::fmt::{self, Display, Formatter};
 use std::io;
+use std::{
+    error::Error as StdError,
+    fmt::{self, Display, Formatter},
+};
 
 /// An enum of all error kinds.
 #[derive(Debug)]
@@ -16,19 +18,15 @@ pub enum Error {
 
 impl Display for Error {
     fn fmt(&self, fmt: &mut Formatter) -> Result<(), fmt::Error> {
-        fmt.write_str(self.description())
+        match *self {
+            Client(ref err) => err.fmt(fmt),
+            Io(ref err) => err.fmt(fmt),
+        }
     }
 }
 
 impl StdError for Error {
-    fn description(&self) -> &str {
-        match *self {
-            Client(err) => err,
-            Io(ref err) => err.description(),
-        }
-    }
-
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             Io(ref err) => Some(&*err),
             _ => None,
@@ -38,13 +36,13 @@ impl StdError for Error {
 
 impl From<io::Error> for Error {
     fn from(err: io::Error) -> Error {
-        Io(err)
+        Error::Io(err)
     }
 }
 
 impl From<&'static str> for Error {
     fn from(string: &'static str) -> Error {
-        Client(string)
+        Error::Client(string)
     }
 }
 

lettre/src/sendmail/mod.rs

@@ -1,11 +1,12 @@
 //! The sendmail transport sends the email using the local sendmail command.
 //!
 
-use {EmailTransport, SendableEmail};
 use sendmail::error::SendmailResult;
-use std::io::Read;
 use std::io::prelude::*;
+use std::io::Read;
 use std::process::{Command, Stdio};
+use SendableEmail;
+use Transport;
 
 pub mod error;
 
@@ -32,22 +33,24 @@ impl SendmailTransport {
     }
 }
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, SendmailResult> for SendmailTransport {
-    fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> SendmailResult {
-        let envelope = email.envelope();
+impl<'a> Transport<'a> for SendmailTransport {
+    type Result = SendmailResult;
+
+    fn send(&mut self, email: SendableEmail) -> SendmailResult {
+        let message_id = email.message_id().to_string();
 
         // Spawn the sendmail command
-        let to_addresses: Vec<String> = envelope.to().iter().map(|x| x.to_string()).collect();
         let mut process = Command::new(&self.command)
-            .args(&[
-                "-i",
-                "-f",
-                &match envelope.from() {
-                    Some(address) => address.to_string(),
-                    None => "\"\"".to_string(),
-                },
-                &to_addresses.join(" "),
-            ])
+            .arg("-i")
+            .arg("-f")
+            .arg(
+                email
+                    .envelope()
+                    .from()
+                    .map(|x| x.as_ref())
+                    .unwrap_or("\"\""),
+            )
+            .args(email.envelope.to())
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
             .spawn()?;
@@ -55,26 +58,21 @@ impl<'a, T: Read + 'a> EmailTransport<'a, T, SendmailResult> for SendmailTranspo
         let mut message_content = String::new();
         let _ = email.message().read_to_string(&mut message_content);
 
-        match process
+        process
             .stdin
             .as_mut()
             .unwrap()
-            .write_all(message_content.as_bytes())
-        {
-            Ok(_) => (),
-            Err(error) => return Err(From::from(error)),
-        }
+            .write_all(message_content.as_bytes())?;
 
-        info!("Wrote message to stdin");
+        info!("Wrote {} message to stdin", message_id);
 
-        if let Ok(output) = process.wait_with_output() {
-            if output.status.success() {
-                Ok(())
-            } else {
-                Err(From::from("The message could not be sent"))
-            }
+        let output = process.wait_with_output()?;
+
+        if output.status.success() {
+            Ok(())
         } else {
-            Err(From::from("The sendmail process stopped"))
+            // TODO display stderr
+            Err(error::Error::Client("The message could not be sent"))
         }
     }
 }

lettre/src/smtp/authentication.rs

@@ -1,31 +1,13 @@
-//! Provides authentication mechanisms
+//! Provides limited SASL authentication mechanisms
 
-#[cfg(feature = "crammd5-auth")]
-use md5::Md5;
-#[cfg(feature = "crammd5-auth")]
-use hmac::{Hmac, Mac};
-#[cfg(feature = "crammd5-auth")]
-use hex;
-use smtp::NUL;
 use smtp::error::Error;
 use std::fmt::{self, Display, Formatter};
 
 /// Accepted authentication mechanisms on an encrypted connection
 /// Trying LOGIN last as it is deprecated.
-#[cfg(feature = "crammd5-auth")]
-pub const DEFAULT_ENCRYPTED_MECHANISMS: &[Mechanism] =
-    &[Mechanism::Plain, Mechanism::CramMd5, Mechanism::Login];
-/// Accepted authentication mechanisms on an encrypted connection
-/// Trying LOGIN last as it is deprecated.
-#[cfg(not(feature = "crammd5-auth"))]
 pub const DEFAULT_ENCRYPTED_MECHANISMS: &[Mechanism] = &[Mechanism::Plain, Mechanism::Login];
 
 /// Accepted authentication mechanisms on an unencrypted connection
-#[cfg(feature = "crammd5-auth")]
-pub const DEFAULT_UNENCRYPTED_MECHANISMS: &[Mechanism] = &[Mechanism::CramMd5];
-/// Accepted authentication mechanisms on an unencrypted connection
-/// When CRAMMD5 support is not enabled, no mechanisms are allowed.
-#[cfg(not(feature = "crammd5-auth"))]
 pub const DEFAULT_UNENCRYPTED_MECHANISMS: &[Mechanism] = &[];
 
 /// Convertable to user credentials
@@ -51,14 +33,17 @@ impl<S: Into<String>, T: Into<String>> IntoCredentials for (S, T) {
 #[derive(PartialEq, Eq, Clone, Hash, Debug)]
 #[cfg_attr(feature = "serde-impls", derive(Serialize, Deserialize))]
 pub struct Credentials {
-    username: String,
-    password: String,
+    authentication_identity: String,
+    secret: String,
 }
 
 impl Credentials {
     /// Create a `Credentials` struct from username and password
     pub fn new(username: String, password: String) -> Credentials {
-        Credentials { username, password }
+        Credentials {
+            authentication_identity: username,
+            secret: password,
+        }
     }
 }
 
@@ -73,10 +58,9 @@ pub enum Mechanism {
     /// Obsolete but needed for some providers (like office365)
     /// https://www.ietf.org/archive/id/draft-murchison-sasl-login-00.txt
     Login,
-    /// CRAM-MD5 authentication mechanism
-    /// RFC 2195: https://tools.ietf.org/html/rfc2195
-    #[cfg(feature = "crammd5-auth")]
-    CramMd5,
+    /// Non-standard XOAUTH2 mechanism
+    /// https://developers.google.com/gmail/imap/xoauth2-protocol
+    Xoauth2,
 }
 
 impl Display for Mechanism {
@@ -87,8 +71,7 @@ impl Display for Mechanism {
             match *self {
                 Mechanism::Plain => "PLAIN",
                 Mechanism::Login => "LOGIN",
-                #[cfg(feature = "crammd5-auth")]
-                Mechanism::CramMd5 => "CRAM-MD5",
+                Mechanism::Xoauth2 => "XOAUTH2",
             }
         )
     }
@@ -96,64 +79,49 @@ impl Display for Mechanism {
 
 impl Mechanism {
     /// Does the mechanism supports initial response
-    #[cfg_attr(feature = "cargo-clippy", allow(match_same_arms))]
-    pub fn supports_initial_response(&self) -> bool {
-        match *self {
-            Mechanism::Plain => true,
+    pub fn supports_initial_response(self) -> bool {
+        match self {
+            Mechanism::Plain | Mechanism::Xoauth2 => true,
             Mechanism::Login => false,
-            #[cfg(feature = "crammd5-auth")]
-            Mechanism::CramMd5 => false,
         }
     }
 
     /// Returns the string to send to the server, using the provided username, password and
     /// challenge in some cases
     pub fn response(
-        &self,
+        self,
         credentials: &Credentials,
         challenge: Option<&str>,
     ) -> Result<String, Error> {
-        match *self {
+        match self {
             Mechanism::Plain => match challenge {
                 Some(_) => Err(Error::Client("This mechanism does not expect a challenge")),
                 None => Ok(format!(
-                    "{}{}{}{}",
-                    NUL, credentials.username, NUL, credentials.password
+                    "\u{0}{}\u{0}{}",
+                    credentials.authentication_identity, credentials.secret
                 )),
             },
             Mechanism::Login => {
-                let decoded_challenge = match challenge {
-                    Some(challenge) => challenge,
-                    None => return Err(Error::Client("This mechanism does expect a challenge")),
-                };
+                let decoded_challenge =
+                    challenge.ok_or(Error::Client("This mechanism does expect a challenge"))?;
 
                 if vec!["User Name", "Username:", "Username"].contains(&decoded_challenge) {
-                    return Ok(credentials.username.to_string());
+                    return Ok(credentials.authentication_identity.to_string());
                 }
 
                 if vec!["Password", "Password:"].contains(&decoded_challenge) {
-                    return Ok(credentials.password.to_string());
+                    return Ok(credentials.secret.to_string());
                 }
 
                 Err(Error::Client("Unrecognized challenge"))
             }
-            #[cfg(feature = "crammd5-auth")]
-            Mechanism::CramMd5 => {
-                let decoded_challenge = match challenge {
-                    Some(challenge) => challenge,
-                    None => return Err(Error::Client("This mechanism does expect a challenge")),
-                };
-
-                let mut hmac: Hmac<Md5> = Hmac::new_varkey(credentials.password.as_bytes())
-                    .expect("md5 should support variable key size");
-                hmac.input(decoded_challenge.as_bytes());
-
-                Ok(format!(
-                    "{} {}",
-                    credentials.username,
-                    hex::encode(hmac.result().code())
-                ))
-            }
+            Mechanism::Xoauth2 => match challenge {
+                Some(_) => Err(Error::Client("This mechanism does not expect a challenge")),
+                None => Ok(format!(
+                    "user={}\x01auth=Bearer {}\x01\x01",
+                    credentials.authentication_identity, credentials.secret
+                )),
+            },
         }
     }
 }
@@ -193,21 +161,18 @@ mod test {
     }
 
     #[test]
-    #[cfg(feature = "crammd5-auth")]
-    fn test_cram_md5() {
-        let mechanism = Mechanism::CramMd5;
+    fn test_xoauth2() {
+        let mechanism = Mechanism::Xoauth2;
 
-        let credentials = Credentials::new("alice".to_string(), "wonderland".to_string());
+        let credentials = Credentials::new(
+            "username".to_string(),
+            "vF9dft4qmTc2Nvb3RlckBhdHRhdmlzdGEuY29tCg==".to_string(),
+        );
 
         assert_eq!(
-            mechanism
-                .response(
-                    &credentials,
-                    Some("PDE3ODkzLjEzMjA2NzkxMjNAdGVzc2VyYWN0LnN1c2FtLmluPg==")
-                )
-                .unwrap(),
-            "alice a540ebe4ef2304070bbc3c456c1f64c0"
+            mechanism.response(&credentials, None).unwrap(),
+            "user=username\x01auth=Bearer vF9dft4qmTc2Nvb3RlckBhdHRhdmlzdGEuY29tCg==\x01\x01"
         );
-        assert!(mechanism.response(&credentials, None).is_err());
+        assert!(mechanism.response(&credentials, Some("test")).is_err());
     }
 }

lettre/src/smtp/client/mod.rs

@@ -2,7 +2,6 @@
 
 use bufstream::BufStream;
 use nom::ErrorKind as NomErrorKind;
-use smtp::{CRLF, MESSAGE_ENDING};
 use smtp::authentication::{Credentials, Mechanism};
 use smtp::client::net::{ClientTlsParameters, Connector, NetworkStream, Timeout};
 use smtp::commands::*;
@@ -14,8 +13,8 @@ use std::net::ToSocketAddrs;
 use std::string::String;
 use std::time::Duration;
 
-pub mod net;
 pub mod mock;
+pub mod net;
 
 /// The codec used for transparency
 #[derive(Default, Clone, Copy, Debug)]
@@ -72,12 +71,12 @@ impl ClientCodec {
 /// Returns the string replacing all the CRLF with "\<CRLF\>"
 /// Used for debug displays
 fn escape_crlf(string: &str) -> String {
-    string.replace(CRLF, "<CRLF>")
+    string.replace("\r\n", "<CRLF>")
 }
 
 /// Structure that implements the SMTP client
 #[derive(Debug, Default)]
-pub struct Client<S: Write + Read = NetworkStream> {
+pub struct InnerClient<S: Write + Read = NetworkStream> {
     /// TCP stream between client and server
     /// Value is None before connection
     stream: Option<BufStream<S>>,
@@ -89,17 +88,17 @@ macro_rules! return_err (
     })
 );
 
-#[cfg_attr(feature = "cargo-clippy", allow(new_without_default_derive))]
-impl<S: Write + Read> Client<S> {
+#[cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default_derive))]
+impl<S: Write + Read> InnerClient<S> {
     /// Creates a new SMTP client
     ///
     /// It does not connects to the server, but only creates the `Client`
-    pub fn new() -> Client<S> {
-        Client { stream: None }
+    pub fn new() -> InnerClient<S> {
+        InnerClient { stream: None }
     }
 }
 
-impl<S: Connector + Write + Read + Timeout + Debug> Client<S> {
+impl<S: Connector + Write + Read + Timeout + Debug> InnerClient<S> {
     /// Closes the SMTP transaction if possible
     pub fn close(&mut self) {
         let _ = self.command(QuitCommand);
@@ -166,9 +165,9 @@ impl<S: Connector + Write + Read + Timeout + Debug> Client<S> {
     }
 
     /// Checks if the server is connected using the NOOP SMTP command
-    #[cfg_attr(feature = "cargo-clippy", allow(wrong_self_convention))]
+    #[cfg_attr(feature = "cargo-clippy", allow(clippy::wrong_self_convention))]
     pub fn is_connected(&mut self) -> bool {
-        self.command(NoopCommand).is_ok()
+        self.stream.is_some() && self.command(NoopCommand).is_ok()
     }
 
     /// Sends an AUTH command with the given mechanism, and handles challenge if needed
@@ -194,10 +193,11 @@ impl<S: Connector + Write + Read + Timeout + Debug> Client<S> {
     }
 
     /// Sends the message content
-    pub fn message<T: Read>(&mut self, mut message: Box<T>) -> SmtpResult {
+    pub fn message(&mut self, message: Box<dyn Read>) -> SmtpResult {
         let mut out_buf: Vec<u8> = vec![];
         let mut codec = ClientCodec::new();
-        let mut message_reader = BufReader::new(message.as_mut());
+
+        let mut message_reader = BufReader::new(message);
 
         loop {
             out_buf.clear();
@@ -218,7 +218,7 @@ impl<S: Connector + Write + Read + Timeout + Debug> Client<S> {
             self.write(out_buf.as_slice())?;
         }
 
-        self.write(MESSAGE_ENDING.as_bytes())?;
+        self.write(b"\r\n.\r\n")?;
         self.read_response()
     }
 
@@ -254,7 +254,13 @@ impl<S: Connector + Write + Read + Timeout + Debug> Client<S> {
                 break;
             }
             // TODO read more than one line
-            self.stream.as_mut().unwrap().read_line(&mut raw_response)?;
+            let read_count = self.stream.as_mut().unwrap().read_line(&mut raw_response)?;
+
+            // EOF is reached
+            if read_count == 0 {
+                break;
+            }
+
             response = raw_response.parse::<Response>();
         }
 

lettre/src/smtp/client/net.rs

@@ -24,8 +24,8 @@ impl ClientTlsParameters {
 }
 
 /// Accepted protocols by default.
-/// This removes TLS 1.0 compared to tls-native defaults.
-pub const DEFAULT_TLS_PROTOCOLS: &[Protocol] = &[Protocol::Tlsv11, Protocol::Tlsv12];
+/// This removes TLS 1.0 and 1.1 compared to tls-native defaults.
+pub const DEFAULT_TLS_PROTOCOLS: &[Protocol] = &[Protocol::Tlsv12];
 
 #[derive(Debug)]
 /// Represents the different types of underlying network streams
@@ -117,7 +117,7 @@ impl Connector for NetworkStream {
         }
     }
 
-    #[cfg_attr(feature = "cargo-clippy", allow(match_same_arms))]
+    #[cfg_attr(feature = "cargo-clippy", allow(clippy::match_same_arms))]
     fn upgrade_tls(&mut self, tls_parameters: &ClientTlsParameters) -> io::Result<()> {
         *self = match *self {
             NetworkStream::Tcp(ref mut stream) => match tls_parameters
@@ -134,7 +134,7 @@ impl Connector for NetworkStream {
         Ok(())
     }
 
-    #[cfg_attr(feature = "cargo-clippy", allow(match_same_arms))]
+    #[cfg_attr(feature = "cargo-clippy", allow(clippy::match_same_arms))]
     fn is_encrypted(&self) -> bool {
         match *self {
             NetworkStream::Tcp(_) => false,

lettre/src/smtp/commands.rs

@@ -1,14 +1,15 @@
+#![cfg_attr(feature = "cargo-clippy", allow(clippy::write_with_newline))]
+
 //! SMTP commands
 
-use EmailAddress;
 use base64;
-use smtp::CRLF;
 use smtp::authentication::{Credentials, Mechanism};
 use smtp::error::Error;
-use smtp::extension::{MailParameter, RcptParameter};
 use smtp::extension::ClientId;
+use smtp::extension::{MailParameter, RcptParameter};
 use smtp::response::Response;
 use std::fmt::{self, Display, Formatter};
+use EmailAddress;
 
 /// EHLO command
 #[derive(PartialEq, Clone, Debug)]
@@ -19,8 +20,7 @@ pub struct EhloCommand {
 
 impl Display for EhloCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "EHLO {}", self.client_id)?;
-        f.write_str(CRLF)
+        write!(f, "EHLO {}\r\n", self.client_id)
     }
 }
 
@@ -38,8 +38,7 @@ pub struct StarttlsCommand;
 
 impl Display for StarttlsCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.write_str("STARTTLS")?;
-        f.write_str(CRLF)
+        f.write_str("STARTTLS\r\n")
     }
 }
 
@@ -56,15 +55,12 @@ impl Display for MailCommand {
         write!(
             f,
             "MAIL FROM:<{}>",
-            match self.sender {
-                Some(ref address) => address.to_string(),
-                None => "".to_string(),
-            }
+            self.sender.as_ref().map(|x| x.as_ref()).unwrap_or("")
         )?;
         for parameter in &self.parameters {
             write!(f, " {}", parameter)?;
         }
-        f.write_str(CRLF)
+        f.write_str("\r\n")
     }
 }
 
@@ -89,7 +85,7 @@ impl Display for RcptCommand {
         for parameter in &self.parameters {
             write!(f, " {}", parameter)?;
         }
-        f.write_str(CRLF)
+        f.write_str("\r\n")
     }
 }
 
@@ -110,8 +106,7 @@ pub struct DataCommand;
 
 impl Display for DataCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.write_str("DATA")?;
-        f.write_str(CRLF)
+        f.write_str("DATA\r\n")
     }
 }
 
@@ -122,8 +117,7 @@ pub struct QuitCommand;
 
 impl Display for QuitCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.write_str("QUIT")?;
-        f.write_str(CRLF)
+        f.write_str("QUIT\r\n")
     }
 }
 
@@ -134,8 +128,7 @@ pub struct NoopCommand;
 
 impl Display for NoopCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.write_str("NOOP")?;
-        f.write_str(CRLF)
+        f.write_str("NOOP\r\n")
     }
 }
 
@@ -152,7 +145,7 @@ impl Display for HelpCommand {
         if self.argument.is_some() {
             write!(f, " {}", self.argument.as_ref().unwrap())?;
         }
-        f.write_str(CRLF)
+        f.write_str("\r\n")
     }
 }
 
@@ -172,8 +165,8 @@ pub struct VrfyCommand {
 
 impl Display for VrfyCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "VRFY {}", self.argument)?;
-        f.write_str(CRLF)
+        #[cfg_attr(feature = "cargo-clippy", allow(clippy::write_with_newline))]
+        write!(f, "VRFY {}\r\n", self.argument)
     }
 }
 
@@ -193,8 +186,7 @@ pub struct ExpnCommand {
 
 impl Display for ExpnCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "EXPN {}", self.argument)?;
-        f.write_str(CRLF)
+        write!(f, "EXPN {}\r\n", self.argument)
     }
 }
 
@@ -212,8 +204,7 @@ pub struct RsetCommand;
 
 impl Display for RsetCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.write_str("RSET")?;
-        f.write_str(CRLF)
+        f.write_str("RSET\r\n")
     }
 }
 
@@ -229,24 +220,20 @@ pub struct AuthCommand {
 
 impl Display for AuthCommand {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        let encoded_response = if self.response.is_some() {
-            Some(base64::encode_config(
-                self.response.as_ref().unwrap().as_bytes(),
-                base64::STANDARD,
-            ))
-        } else {
-            None
-        };
+        let encoded_response = self
+            .response
+            .as_ref()
+            .map(|r| base64::encode_config(r.as_bytes(), base64::STANDARD));
 
         if self.mechanism.supports_initial_response() {
-            write!(f, "AUTH {} {}", self.mechanism, encoded_response.unwrap(),)?;
+            write!(f, "AUTH {} {}", self.mechanism, encoded_response.unwrap())?;
         } else {
             match encoded_response {
                 Some(response) => f.write_str(&response)?,
                 None => write!(f, "AUTH {}", self.mechanism)?,
             }
         }
-        f.write_str(CRLF)
+        f.write_str("\r\n")
     }
 }
 
@@ -258,7 +245,7 @@ impl AuthCommand {
         challenge: Option<String>,
     ) -> Result<AuthCommand, Error> {
         let response = if mechanism.supports_initial_response() || challenge.is_some() {
-            Some(mechanism.response(&credentials, challenge.as_ref().map(String::as_str))?)
+            Some(mechanism.response(&credentials, challenge.as_deref())?)
         } else {
             None
         };
@@ -281,21 +268,12 @@ impl AuthCommand {
             return Err(Error::ResponseParsing("Expecting a challenge"));
         }
 
-        let encoded_challenge = match response.first_word() {
-            Some(challenge) => challenge.to_string(),
-            None => return Err(Error::ResponseParsing("Could not read auth challenge")),
-        };
-
+        let encoded_challenge = response
+            .first_word()
+            .ok_or(Error::ResponseParsing("Could not read auth challenge"))?;
         debug!("auth encoded challenge: {}", encoded_challenge);
 
-        let decoded_challenge = match base64::decode(&encoded_challenge) {
-            Ok(challenge) => match String::from_utf8(challenge) {
-                Ok(value) => value,
-                Err(error) => return Err(Error::Utf8Parsing(error)),
-            },
-            Err(error) => return Err(Error::ChallengeParsing(error)),
-        };
-
+        let decoded_challenge = String::from_utf8(base64::decode(&encoded_challenge)?)?;
         debug!("auth decoded challenge: {}", decoded_challenge);
 
         let response = Some(mechanism.response(&credentials, Some(decoded_challenge.as_ref()))?);
@@ -313,8 +291,6 @@ impl AuthCommand {
 mod test {
     use super::*;
     use smtp::extension::MailBodyParameter;
-    #[cfg(feature = "crammd5-auth")]
-    use smtp::response::{Category, Code, Detail, Severity};
 
     #[test]
     fn test_display() {
@@ -391,18 +367,6 @@ mod test {
             ),
             "AUTH PLAIN AHVzZXIAcGFzc3dvcmQ=\r\n"
         );
-        #[cfg(feature = "crammd5-auth")]
-        assert_eq!(
-            format!(
-                "{}",
-                AuthCommand::new(
-                    Mechanism::CramMd5,
-                    credentials.clone(),
-                    Some("test".to_string()),
-                ).unwrap()
-            ),
-            "dXNlciAzMTYxY2NmZDdmMjNlMzJiYmMzZTQ4NjdmYzk0YjE4Nw==\r\n"
-        );
         assert_eq!(
             format!(
                 "{}",
@@ -410,24 +374,5 @@ mod test {
             ),
             "AUTH LOGIN\r\n"
         );
-        #[cfg(feature = "crammd5-auth")]
-        assert_eq!(
-            format!(
-                "{}",
-                AuthCommand::new_from_response(
-                    Mechanism::CramMd5,
-                    credentials.clone(),
-                    &Response::new(
-                        Code::new(
-                            Severity::PositiveIntermediate,
-                            Category::Unspecified3,
-                            Detail::Four,
-                        ),
-                        vec!["dGVzdAo=".to_string()],
-                    ),
-                ).unwrap()
-            ),
-            "dXNlciA1NTIzNThiMzExOWFjOWNkYzM2YWRiN2MxNWRmMWJkNw==\r\n"
-        );
     }
 }

lettre/src/smtp/error.rs

@@ -37,47 +37,41 @@ pub enum Error {
     /// TLS error
     Tls(native_tls::Error),
     /// Parsing error
-    Parsing(nom::simple_errors::Err),
+    Parsing(nom::ErrorKind),
 }
 
 impl Display for Error {
     fn fmt(&self, fmt: &mut Formatter) -> Result<(), fmt::Error> {
-        fmt.write_str(self.description())
+        match *self {
+            // Try to display the first line of the server's response that usually
+            // contains a short humanly readable error message
+            Transient(ref err) => fmt.write_str(match err.first_line() {
+                Some(line) => line,
+                None => "transient error during SMTP transaction",
+            }),
+            Permanent(ref err) => fmt.write_str(match err.first_line() {
+                Some(line) => line,
+                None => "permanent error during SMTP transaction",
+            }),
+            ResponseParsing(err) => fmt.write_str(err),
+            ChallengeParsing(ref err) => err.fmt(fmt),
+            Utf8Parsing(ref err) => err.fmt(fmt),
+            Resolution => fmt.write_str("could not resolve hostname"),
+            Client(err) => fmt.write_str(err),
+            Io(ref err) => err.fmt(fmt),
+            Tls(ref err) => err.fmt(fmt),
+            Parsing(ref err) => fmt.write_str(err.description()),
+        }
     }
 }
 
 impl StdError for Error {
-    #[cfg_attr(feature = "cargo-clippy", allow(match_same_arms))]
-    fn description(&self) -> &str {
-        match *self {
-            // Try to display the first line of the server's response that usually
-            // contains a short humanly readable error message
-            Transient(ref err) => match err.first_line() {
-                Some(line) => line,
-                None => "undetailed transient error during SMTP transaction",
-            },
-            Permanent(ref err) => match err.first_line() {
-                Some(line) => line,
-                None => "undetailed permanent error during SMTP transaction",
-            },
-            ResponseParsing(err) => err,
-            ChallengeParsing(ref err) => err.description(),
-            Utf8Parsing(ref err) => err.description(),
-            Resolution => "could not resolve hostname",
-            Client(err) => err,
-            Io(ref err) => err.description(),
-            Tls(ref err) => err.description(),
-            Parsing(ref err) => err.description(),
-        }
-    }
-
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             ChallengeParsing(ref err) => Some(&*err),
             Utf8Parsing(ref err) => Some(&*err),
             Io(ref err) => Some(&*err),
             Tls(ref err) => Some(&*err),
-            Parsing(ref err) => Some(&*err),
             _ => None,
         }
     }
@@ -95,12 +89,24 @@ impl From<native_tls::Error> for Error {
     }
 }
 
-impl From<nom::simple_errors::Err> for Error {
-    fn from(err: nom::simple_errors::Err) -> Error {
+impl From<nom::ErrorKind> for Error {
+    fn from(err: nom::ErrorKind) -> Error {
         Parsing(err)
     }
 }
 
+impl From<DecodeError> for Error {
+    fn from(err: DecodeError) -> Error {
+        ChallengeParsing(err)
+    }
+}
+
+impl From<FromUtf8Error> for Error {
+    fn from(err: FromUtf8Error) -> Error {
+        Utf8Parsing(err)
+    }
+}
+
 impl From<Response> for Error {
     fn from(response: Response) -> Error {
         match response.code.severity {

lettre/src/smtp/extension.rs

@@ -10,8 +10,8 @@ use std::fmt::{self, Display, Formatter};
 use std::net::{Ipv4Addr, Ipv6Addr};
 use std::result::Result;
 
-/// Default ehlo clinet id
-pub const DEFAULT_EHLO_HOSTNAME: &str = "localhost";
+/// Default client id
+pub const DEFAULT_DOMAIN_CLIENT_ID: &str = "localhost";
 
 /// Client identifier, the parameter to `EHLO`
 #[derive(PartialEq, Eq, Clone, Debug)]
@@ -44,10 +44,7 @@ impl ClientId {
     /// Defines a `ClientId` with the current hostname, of `localhost` if hostname could not be
     /// found
     pub fn hostname() -> ClientId {
-        ClientId::Domain(match get_hostname() {
-            Some(name) => name,
-            None => DEFAULT_EHLO_HOSTNAME.to_string(),
-        })
+        ClientId::Domain(get_hostname().unwrap_or_else(|| DEFAULT_DOMAIN_CLIENT_ID.to_string()))
     }
 }
 
@@ -137,21 +134,22 @@ impl ServerInfo {
                 "STARTTLS" => {
                     features.insert(Extension::StartTls);
                 }
-                "AUTH" => for &mechanism in &split[1..] {
-                    match mechanism {
-                        "PLAIN" => {
-                            features.insert(Extension::Authentication(Mechanism::Plain));
+                "AUTH" => {
+                    for &mechanism in &split[1..] {
+                        match mechanism {
+                            "PLAIN" => {
+                                features.insert(Extension::Authentication(Mechanism::Plain));
+                            }
+                            "LOGIN" => {
+                                features.insert(Extension::Authentication(Mechanism::Login));
+                            }
+                            "XOAUTH2" => {
+                                features.insert(Extension::Authentication(Mechanism::Xoauth2));
+                            }
+                            _ => (),
                         }
-                        "LOGIN" => {
-                            features.insert(Extension::Authentication(Mechanism::Login));
-                        }
-                        #[cfg(feature = "crammd5-auth")]
-                        "CRAM-MD5" => {
-                            features.insert(Extension::Authentication(Mechanism::CramMd5));
-                        }
-                        _ => (),
                     }
-                },
+                }
                 _ => (),
             };
         }
@@ -357,8 +355,6 @@ mod test {
 
         assert!(server_info.supports_feature(Extension::EightBitMime));
         assert!(!server_info.supports_feature(Extension::StartTls));
-        #[cfg(feature = "crammd5-auth")]
-        assert!(!server_info.supports_auth_mechanism(Mechanism::CramMd5));
 
         let response2 = Response::new(
             Code::new(
@@ -368,7 +364,7 @@ mod test {
             ),
             vec![
                 "me".to_string(),
-                "AUTH PLAIN CRAM-MD5 OTHER".to_string(),
+                "AUTH PLAIN CRAM-MD5 XOAUTH2 OTHER".to_string(),
                 "8BITMIME".to_string(),
                 "SIZE 42".to_string(),
             ],
@@ -377,8 +373,7 @@ mod test {
         let mut features2 = HashSet::new();
         assert!(features2.insert(Extension::EightBitMime));
         assert!(features2.insert(Extension::Authentication(Mechanism::Plain),));
-        #[cfg(feature = "crammd5-auth")]
-        assert!(features2.insert(Extension::Authentication(Mechanism::CramMd5),));
+        assert!(features2.insert(Extension::Authentication(Mechanism::Xoauth2),));
 
         let server_info2 = ServerInfo {
             name: "me".to_string(),
@@ -389,8 +384,6 @@ mod test {
 
         assert!(server_info2.supports_feature(Extension::EightBitMime));
         assert!(server_info2.supports_auth_mechanism(Mechanism::Plain));
-        #[cfg(feature = "crammd5-auth")]
-        assert!(server_info2.supports_auth_mechanism(Mechanism::CramMd5));
         assert!(!server_info2.supports_feature(Extension::StartTls));
     }
 }

lettre/src/smtp/mod.rs

@@ -8,33 +8,33 @@
 //! It implements the following extensions:
 //!
 //! * 8BITMIME ([RFC 6152](https://tools.ietf.org/html/rfc6152))
-//! * AUTH ([RFC 4954](http://tools.ietf.org/html/rfc4954)) with PLAIN, LOGIN and
-//! CRAM-MD5 mechanisms
+//! * AUTH ([RFC 4954](http://tools.ietf.org/html/rfc4954)) with PLAIN, LOGIN and XOAUTH2 mechanisms
 //! * STARTTLS ([RFC 2487](http://tools.ietf.org/html/rfc2487))
 //! * SMTPUTF8 ([RFC 6531](http://tools.ietf.org/html/rfc6531))
 //!
 
-use EmailTransport;
-use SendableEmail;
 use native_tls::TlsConnector;
-use smtp::authentication::{Credentials, Mechanism, DEFAULT_ENCRYPTED_MECHANISMS,
-                           DEFAULT_UNENCRYPTED_MECHANISMS};
-use smtp::client::Client;
+use smtp::authentication::{
+    Credentials, Mechanism, DEFAULT_ENCRYPTED_MECHANISMS, DEFAULT_UNENCRYPTED_MECHANISMS,
+};
 use smtp::client::net::ClientTlsParameters;
 use smtp::client::net::DEFAULT_TLS_PROTOCOLS;
+use smtp::client::InnerClient;
 use smtp::commands::*;
 use smtp::error::{Error, SmtpResult};
 use smtp::extension::{ClientId, Extension, MailBodyParameter, MailParameter, ServerInfo};
-use std::io::Read;
 use std::net::{SocketAddr, ToSocketAddrs};
 use std::time::Duration;
+use {SendableEmail, Transport};
 
-pub mod extension;
-pub mod commands;
 pub mod authentication;
-pub mod response;
 pub mod client;
+pub mod commands;
 pub mod error;
+pub mod extension;
+#[cfg(feature = "connection-pool")]
+pub mod r2d2;
+pub mod response;
 pub mod util;
 
 // Registered port numbers:
@@ -43,39 +43,22 @@ pub mod util;
 
 /// Default smtp port
 pub const SMTP_PORT: u16 = 25;
-
 /// Default submission port
 pub const SUBMISSION_PORT: u16 = 587;
-
-// Useful strings and characters
-
-/// The word separator for SMTP transactions
-pub const SP: &str = " ";
-
-/// The line ending for SMTP transactions (carriage return + line feed)
-pub const CRLF: &str = "\r\n";
-
-/// Colon
-pub const COLON: &str = ":";
-
-/// The ending of message content
-pub const MESSAGE_ENDING: &str = "\r\n.\r\n";
-
-/// NUL unicode character
-pub const NUL: &str = "\0";
+/// Default submission over TLS port
+pub const SUBMISSIONS_PORT: u16 = 465;
 
 /// How to apply TLS to a client connection
 #[derive(Clone)]
 #[allow(missing_debug_implementations)]
 pub enum ClientSecurity {
-    /// Insecure connection
+    /// Insecure connection only (for testing purposes)
     None,
-    /// Use `STARTTLS` when available
+    /// Start with insecure connection and use `STARTTLS` when available
     Opportunistic(ClientTlsParameters),
-    /// Always use `STARTTLS`
+    /// Start with insecure connection and require `STARTTLS`
     Required(ClientTlsParameters),
-    /// Use TLS wrapped connection without negotiation
-    /// Non RFC-compliant, should only be used if the server does not support STARTTLS.
+    /// Use TLS wrapped connection
     Wrapper(ClientTlsParameters),
 }
 
@@ -93,7 +76,8 @@ pub enum ConnectionReuseParameters {
 
 /// Contains client configuration
 #[allow(missing_debug_implementations)]
-pub struct SmtpTransportBuilder {
+#[derive(Clone)]
+pub struct SmtpClient {
     /// Enable connection reuse
     connection_reuse: ConnectionReuseParameters,
     /// Name sent during EHLO
@@ -114,7 +98,7 @@ pub struct SmtpTransportBuilder {
 }
 
 /// Builder for the SMTP `SmtpTransport`
-impl SmtpTransportBuilder {
+impl SmtpClient {
     /// Creates a new SMTP client
     ///
     /// Defaults are:
@@ -123,14 +107,13 @@ impl SmtpTransportBuilder {
     /// * No authentication
     /// * No SMTPUTF8 support
     /// * A 60 seconds timeout for smtp commands
-    pub fn new<A: ToSocketAddrs>(
-        addr: A,
-        security: ClientSecurity,
-    ) -> Result<SmtpTransportBuilder, Error> {
+    ///
+    /// Consider using [`SmtpClient::new_simple`] instead, if possible.
+    pub fn new<A: ToSocketAddrs>(addr: A, security: ClientSecurity) -> Result<SmtpClient, Error> {
         let mut addresses = addr.to_socket_addrs()?;
 
         match addresses.next() {
-            Some(addr) => Ok(SmtpTransportBuilder {
+            Some(addr) => Ok(SmtpClient {
                 server_addr: addr,
                 security,
                 smtp_utf8: false,
@@ -144,41 +127,59 @@ impl SmtpTransportBuilder {
         }
     }
 
+    /// Simple and secure transport, should be used when possible.
+    /// Creates an encrypted transport over submissions port, using the provided domain
+    /// to validate TLS certificates.
+    pub fn new_simple(domain: &str) -> Result<SmtpClient, Error> {
+        let mut tls_builder = TlsConnector::builder();
+        tls_builder.min_protocol_version(Some(DEFAULT_TLS_PROTOCOLS[0]));
+
+        let tls_parameters =
+            ClientTlsParameters::new(domain.to_string(), tls_builder.build().unwrap());
+
+        SmtpClient::new(
+            (domain, SUBMISSIONS_PORT),
+            ClientSecurity::Wrapper(tls_parameters),
+        )
+    }
+
+    /// Creates a new local SMTP client to port 25
+    pub fn new_unencrypted_localhost() -> Result<SmtpClient, Error> {
+        SmtpClient::new(("localhost", SMTP_PORT), ClientSecurity::None)
+    }
+
     /// Enable SMTPUTF8 if the server supports it
-    pub fn smtp_utf8(mut self, enabled: bool) -> SmtpTransportBuilder {
+    pub fn smtp_utf8(mut self, enabled: bool) -> SmtpClient {
         self.smtp_utf8 = enabled;
         self
     }
 
     /// Set the name used during EHLO
-    pub fn hello_name(mut self, name: ClientId) -> SmtpTransportBuilder {
+    pub fn hello_name(mut self, name: ClientId) -> SmtpClient {
         self.hello_name = name;
         self
     }
 
     /// Enable connection reuse
-    pub fn connection_reuse(
-        mut self,
-        parameters: ConnectionReuseParameters,
-    ) -> SmtpTransportBuilder {
+    pub fn connection_reuse(mut self, parameters: ConnectionReuseParameters) -> SmtpClient {
         self.connection_reuse = parameters;
         self
     }
 
     /// Set the client credentials
-    pub fn credentials<S: Into<Credentials>>(mut self, credentials: S) -> SmtpTransportBuilder {
+    pub fn credentials<S: Into<Credentials>>(mut self, credentials: S) -> SmtpClient {
         self.credentials = Some(credentials.into());
         self
     }
 
     /// Set the authentication mechanism to use
-    pub fn authentication_mechanism(mut self, mechanism: Mechanism) -> SmtpTransportBuilder {
+    pub fn authentication_mechanism(mut self, mechanism: Mechanism) -> SmtpClient {
         self.authentication_mechanism = Some(mechanism);
         self
     }
 
     /// Set the timeout duration
-    pub fn timeout(mut self, timeout: Option<Duration>) -> SmtpTransportBuilder {
+    pub fn timeout(mut self, timeout: Option<Duration>) -> SmtpClient {
         self.timeout = timeout;
         self
     }
@@ -186,7 +187,7 @@ impl SmtpTransportBuilder {
     /// Build the SMTP client
     ///
     /// It does not connect to the server, but only creates the `SmtpTransport`
-    pub fn build(self) -> SmtpTransport {
+    pub fn transport(self) -> SmtpTransport {
         SmtpTransport::new(self)
     }
 }
@@ -209,9 +210,9 @@ pub struct SmtpTransport {
     /// SmtpTransport variable states
     state: State,
     /// Information about the client
-    client_info: SmtpTransportBuilder,
+    client_info: SmtpClient,
     /// Low level client
-    client: Client,
+    client: InnerClient,
 }
 
 macro_rules! try_smtp (
@@ -230,40 +231,11 @@ macro_rules! try_smtp (
 );
 
 impl<'a> SmtpTransport {
-    /// Simple and secure transport, should be used when possible.
-    /// Creates an encrypted transport over submission port, using the provided domain
-    /// to validate TLS certificates.
-    pub fn simple_builder(domain: &str) -> Result<SmtpTransportBuilder, Error> {
-        let mut tls_builder = TlsConnector::builder()?;
-        tls_builder.supported_protocols(DEFAULT_TLS_PROTOCOLS)?;
-
-        let tls_parameters =
-            ClientTlsParameters::new(domain.to_string(), tls_builder.build().unwrap());
-
-        SmtpTransportBuilder::new(
-            (domain, SUBMISSION_PORT),
-            ClientSecurity::Required(tls_parameters),
-        )
-    }
-
-    /// Creates a new configurable builder
-    pub fn builder<A: ToSocketAddrs>(
-        addr: A,
-        security: ClientSecurity,
-    ) -> Result<SmtpTransportBuilder, Error> {
-        SmtpTransportBuilder::new(addr, security)
-    }
-
-    /// Creates a new local SMTP client to port 25
-    pub fn builder_unencrypted_localhost() -> Result<SmtpTransportBuilder, Error> {
-        SmtpTransportBuilder::new(("localhost", SMTP_PORT), ClientSecurity::None)
-    }
-
     /// Creates a new SMTP client
     ///
     /// It does not connect to the server, but only creates the `SmtpTransport`
-    pub fn new(builder: SmtpTransportBuilder) -> SmtpTransport {
-        let client = Client::new();
+    pub fn new(builder: SmtpClient) -> SmtpTransport {
+        let client = InnerClient::new();
 
         SmtpTransport {
             client,
@@ -276,6 +248,99 @@ impl<'a> SmtpTransport {
         }
     }
 
+    fn connect(&mut self) -> Result<(), Error> {
+        // Check if the connection is still available
+        if (self.state.connection_reuse_count > 0) && (!self.client.is_connected()) {
+            self.close();
+        }
+
+        if self.state.connection_reuse_count > 0 {
+            info!(
+                "connection already established to {}",
+                self.client_info.server_addr
+            );
+            return Ok(());
+        }
+
+        self.client.connect(
+            &self.client_info.server_addr,
+            match self.client_info.security {
+                ClientSecurity::Wrapper(ref tls_parameters) => Some(tls_parameters),
+                _ => None,
+            },
+        )?;
+
+        self.client.set_timeout(self.client_info.timeout)?;
+
+        // Log the connection
+        info!("connection established to {}", self.client_info.server_addr);
+
+        self.ehlo()?;
+
+        match (
+            &self.client_info.security.clone(),
+            self.server_info
+                .as_ref()
+                .unwrap()
+                .supports_feature(Extension::StartTls),
+        ) {
+            (&ClientSecurity::Required(_), false) => {
+                return Err(From::from("Could not encrypt connection, aborting"));
+            }
+            (&ClientSecurity::Opportunistic(_), false) => (),
+            (&ClientSecurity::None, _) => (),
+            (&ClientSecurity::Wrapper(_), _) => (),
+            (&ClientSecurity::Opportunistic(ref tls_parameters), true)
+            | (&ClientSecurity::Required(ref tls_parameters), true) => {
+                try_smtp!(self.client.command(StarttlsCommand), self);
+                try_smtp!(self.client.upgrade_tls_stream(tls_parameters), self);
+
+                debug!("connection encrypted");
+
+                // Send EHLO again
+                self.ehlo()?;
+            }
+        }
+
+        if self.client_info.credentials.is_some() {
+            let mut found = false;
+
+            // Compute accepted mechanism
+            let accepted_mechanisms = match self.client_info.authentication_mechanism {
+                Some(mechanism) => vec![mechanism],
+                None => {
+                    if self.client.is_encrypted() {
+                        DEFAULT_ENCRYPTED_MECHANISMS.to_vec()
+                    } else {
+                        DEFAULT_UNENCRYPTED_MECHANISMS.to_vec()
+                    }
+                }
+            };
+
+            for mechanism in accepted_mechanisms {
+                if self
+                    .server_info
+                    .as_ref()
+                    .unwrap()
+                    .supports_auth_mechanism(mechanism)
+                {
+                    found = true;
+                    try_smtp!(
+                        self.client
+                            .auth(mechanism, self.client_info.credentials.as_ref().unwrap(),),
+                        self
+                    );
+                    break;
+                }
+            }
+
+            if !found {
+                info!("No supported authentication mechanisms available");
+            }
+        }
+        Ok(())
+    }
+
     /// Gets the EHLO response and updates server information
     fn ehlo(&mut self) -> SmtpResult {
         // Extended Hello
@@ -306,101 +371,26 @@ impl<'a> SmtpTransport {
     }
 }
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, SmtpResult> for SmtpTransport {
+impl<'a> Transport<'a> for SmtpTransport {
+    type Result = SmtpResult;
+
     /// Sends an email
-    #[cfg_attr(feature = "cargo-clippy", allow(match_same_arms, cyclomatic_complexity))]
-    fn send<U: SendableEmail<'a, T> + 'a>(&mut self, email: &'a U) -> SmtpResult {
-        // Extract email information
-        let message_id = email.message_id();
-        let envelope = email.envelope();
+    #[cfg_attr(
+        feature = "cargo-clippy",
+        allow(clippy::match_same_arms, clippy::cyclomatic_complexity)
+    )]
+    fn send(&mut self, email: SendableEmail) -> SmtpResult {
+        let message_id = email.message_id().to_string();
 
-        // Check if the connection is still available
-        if (self.state.connection_reuse_count > 0) && (!self.client.is_connected()) {
-            self.close();
-        }
-
-        if self.state.connection_reuse_count == 0 {
-            self.client.connect(
-                &self.client_info.server_addr,
-                match self.client_info.security {
-                    ClientSecurity::Wrapper(ref tls_parameters) => Some(tls_parameters),
-                    _ => None,
-                },
-            )?;
-
-            self.client.set_timeout(self.client_info.timeout)?;
-
-            // Log the connection
-            info!("connection established to {}", self.client_info.server_addr);
-
-            self.ehlo()?;
-
-            match (
-                &self.client_info.security.clone(),
-                self.server_info
-                    .as_ref()
-                    .unwrap()
-                    .supports_feature(Extension::StartTls),
-            ) {
-                (&ClientSecurity::Required(_), false) => {
-                    return Err(From::from("Could not encrypt connection, aborting"))
-                }
-                (&ClientSecurity::Opportunistic(_), false) => (),
-                (&ClientSecurity::None, _) => (),
-                (&ClientSecurity::Wrapper(_), _) => (),
-                (&ClientSecurity::Opportunistic(ref tls_parameters), true)
-                | (&ClientSecurity::Required(ref tls_parameters), true) => {
-                    try_smtp!(self.client.command(StarttlsCommand), self);
-                    try_smtp!(self.client.upgrade_tls_stream(tls_parameters), self);
-
-                    debug!("connection encrypted");
-
-                    // Send EHLO again
-                    self.ehlo()?;
-                }
-            }
-
-            if self.client_info.credentials.is_some() {
-                let mut found = false;
-
-                // Compute accepted mechanism
-                let accepted_mechanisms = match self.client_info.authentication_mechanism {
-                    Some(mechanism) => vec![mechanism],
-                    None => {
-                        if self.client.is_encrypted() {
-                            DEFAULT_ENCRYPTED_MECHANISMS.to_vec()
-                        } else {
-                            DEFAULT_UNENCRYPTED_MECHANISMS.to_vec()
-                        }
-                    }
-                };
-
-                for mechanism in accepted_mechanisms {
-                    if self.server_info
-                        .as_ref()
-                        .unwrap()
-                        .supports_auth_mechanism(mechanism)
-                    {
-                        found = true;
-                        try_smtp!(
-                            self.client
-                                .auth(mechanism, self.client_info.credentials.as_ref().unwrap(),),
-                            self
-                        );
-                        break;
-                    }
-                }
-
-                if !found {
-                    info!("No supported authentication mechanisms available");
-                }
-            }
+        if !self.client.is_connected() {
+            self.connect()?;
         }
 
         // Mail
         let mut mail_options = vec![];
 
-        if self.server_info
+        if self
+            .server_info
             .as_ref()
             .unwrap()
             .supports_feature(Extension::EightBitMime)
@@ -408,17 +398,21 @@ impl<'a, T: Read + 'a> EmailTransport<'a, T, SmtpResult> for SmtpTransport {
             mail_options.push(MailParameter::Body(MailBodyParameter::EightBitMime));
         }
 
-        if self.server_info
+        if self
+            .server_info
             .as_ref()
             .unwrap()
-            .supports_feature(Extension::SmtpUtfEight) && self.client_info.smtp_utf8
+            .supports_feature(Extension::SmtpUtfEight)
+            && self.client_info.smtp_utf8
         {
             mail_options.push(MailParameter::SmtpUtfEight);
         }
 
         try_smtp!(
-            self.client
-                .command(MailCommand::new(envelope.from().cloned(), mail_options,)),
+            self.client.command(MailCommand::new(
+                email.envelope().from().cloned(),
+                mail_options,
+            )),
             self
         );
 
@@ -426,17 +420,17 @@ impl<'a, T: Read + 'a> EmailTransport<'a, T, SmtpResult> for SmtpTransport {
         info!(
             "{}: from=<{}>",
             message_id,
-            match envelope.from() {
+            match email.envelope().from() {
                 Some(address) => address.to_string(),
                 None => "".to_string(),
             }
         );
 
         // Recipient
-        for to_address in envelope.to() {
+        for to_address in email.envelope().to() {
             try_smtp!(
                 self.client
-                    .command(RcptCommand::new(to_address.clone(), vec![]),),
+                    .command(RcptCommand::new(to_address.clone(), vec![])),
                 self
             );
             // Log the rcpt command
@@ -447,7 +441,7 @@ impl<'a, T: Read + 'a> EmailTransport<'a, T, SmtpResult> for SmtpTransport {
         try_smtp!(self.client.command(DataCommand), self);
 
         // Message content
-        let result = self.client.message(email.message());
+        let result = self.client.message(Box::new(email.message()));
 
         if result.is_ok() {
             // Increment the connection reuse counter

lettre/src/smtp/r2d2.rs

@@ -0,0 +1,38 @@
+use r2d2::ManageConnection;
+use smtp::error::Error;
+use smtp::{ConnectionReuseParameters, SmtpClient, SmtpTransport};
+
+pub struct SmtpConnectionManager {
+    transport_builder: SmtpClient,
+}
+
+impl SmtpConnectionManager {
+    pub fn new(transport_builder: SmtpClient) -> Result<SmtpConnectionManager, Error> {
+        Ok(SmtpConnectionManager {
+            transport_builder: transport_builder
+                .connection_reuse(ConnectionReuseParameters::ReuseUnlimited),
+        })
+    }
+}
+
+impl ManageConnection for SmtpConnectionManager {
+    type Connection = SmtpTransport;
+    type Error = Error;
+
+    fn connect(&self) -> Result<Self::Connection, Error> {
+        let mut transport = SmtpTransport::new(self.transport_builder.clone());
+        transport.connect()?;
+        Ok(transport)
+    }
+
+    fn is_valid(&self, conn: &mut Self::Connection) -> Result<(), Error> {
+        if conn.client.is_connected() {
+            return Ok(());
+        }
+        Err(Error::Client("is not connected anymore"))
+    }
+
+    fn has_broken(&self, conn: &mut Self::Connection) -> bool {
+        conn.state.panic
+    }
+}

lettre/src/smtp/response.rs

@@ -1,11 +1,10 @@
 //! SMTP response, containing a mandatory return code and an optional text
 //! message
 
-use nom::{crlf, ErrorKind as NomErrorKind, IResult as NomResult};
-use nom::simple_errors::Err as NomError;
+use nom::{crlf, ErrorKind as NomErrorKind};
 use std::fmt::{Display, Formatter, Result};
 use std::result;
-use std::str::{FromStr, from_utf8};
+use std::str::{from_utf8, FromStr};
 
 /// First digit indicates severity
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
@@ -126,13 +125,12 @@ pub struct Response {
 }
 
 impl FromStr for Response {
-    type Err = NomError;
+    type Err = NomErrorKind;
 
-    fn from_str(s: &str) -> result::Result<Response, NomError> {
+    fn from_str(s: &str) -> result::Result<Response, NomErrorKind> {
         match parse_response(s.as_bytes()) {
-            NomResult::Done(_, res) => Ok(res),
-            NomResult::Error(e) => Err(e),
-            NomResult::Incomplete(_) => Err(NomErrorKind::Complete),
+            Ok((_, res)) => Ok(res),
+            Err(e) => Err(e.into_error_kind()),
         }
     }
 }
@@ -333,20 +331,19 @@ mod test {
 
     #[test]
     fn test_response_is_positive() {
-        assert!(
-            Response::new(
-                Code {
-                    severity: Severity::PositiveCompletion,
-                    category: Category::MailSystem,
-                    detail: Detail::Zero,
-                },
-                vec![
-                    "me".to_string(),
-                    "8BITMIME".to_string(),
-                    "SIZE 42".to_string(),
-                ],
-            ).is_positive()
-        );
+        assert!(Response::new(
+            Code {
+                severity: Severity::PositiveCompletion,
+                category: Category::MailSystem,
+                detail: Detail::Zero,
+            },
+            vec![
+                "me".to_string(),
+                "8BITMIME".to_string(),
+                "SIZE 42".to_string(),
+            ],
+        )
+        .is_positive());
         assert!(!Response::new(
             Code {
                 severity: Severity::TransientNegativeCompletion,
@@ -358,25 +355,25 @@ mod test {
                 "8BITMIME".to_string(),
                 "SIZE 42".to_string(),
             ],
-        ).is_positive());
+        )
+        .is_positive());
     }
 
     #[test]
     fn test_response_has_code() {
-        assert!(
-            Response::new(
-                Code {
-                    severity: Severity::TransientNegativeCompletion,
-                    category: Category::MailSystem,
-                    detail: Detail::One,
-                },
-                vec![
-                    "me".to_string(),
-                    "8BITMIME".to_string(),
-                    "SIZE 42".to_string(),
-                ],
-            ).has_code(451)
-        );
+        assert!(Response::new(
+            Code {
+                severity: Severity::TransientNegativeCompletion,
+                category: Category::MailSystem,
+                detail: Detail::One,
+            },
+            vec![
+                "me".to_string(),
+                "8BITMIME".to_string(),
+                "SIZE 42".to_string(),
+            ],
+        )
+        .has_code(451));
         assert!(!Response::new(
             Code {
                 severity: Severity::TransientNegativeCompletion,
@@ -388,7 +385,8 @@ mod test {
                 "8BITMIME".to_string(),
                 "SIZE 42".to_string(),
             ],
-        ).has_code(251));
+        )
+        .has_code(251));
     }
 
     #[test]
@@ -405,7 +403,8 @@ mod test {
                     "8BITMIME".to_string(),
                     "SIZE 42".to_string(),
                 ],
-            ).first_word(),
+            )
+            .first_word(),
             Some("me")
         );
         assert_eq!(
@@ -420,7 +419,8 @@ mod test {
                     "8BITMIME".to_string(),
                     "SIZE 42".to_string(),
                 ],
-            ).first_word(),
+            )
+            .first_word(),
             Some("me")
         );
         assert_eq!(
@@ -431,7 +431,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec![],
-            ).first_word(),
+            )
+            .first_word(),
             None
         );
         assert_eq!(
@@ -442,7 +443,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec![" ".to_string()],
-            ).first_word(),
+            )
+            .first_word(),
             None
         );
         assert_eq!(
@@ -453,7 +455,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec!["  ".to_string()],
-            ).first_word(),
+            )
+            .first_word(),
             None
         );
         assert_eq!(
@@ -464,7 +467,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec!["".to_string()],
-            ).first_word(),
+            )
+            .first_word(),
             None
         );
     }
@@ -483,7 +487,8 @@ mod test {
                     "8BITMIME".to_string(),
                     "SIZE 42".to_string(),
                 ],
-            ).first_line(),
+            )
+            .first_line(),
             Some("me")
         );
         assert_eq!(
@@ -498,7 +503,8 @@ mod test {
                     "8BITMIME".to_string(),
                     "SIZE 42".to_string(),
                 ],
-            ).first_line(),
+            )
+            .first_line(),
             Some("me mo")
         );
         assert_eq!(
@@ -509,7 +515,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec![],
-            ).first_line(),
+            )
+            .first_line(),
             None
         );
         assert_eq!(
@@ -520,7 +527,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec![" ".to_string()],
-            ).first_line(),
+            )
+            .first_line(),
             Some(" ")
         );
         assert_eq!(
@@ -531,7 +539,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec!["  ".to_string()],
-            ).first_line(),
+            )
+            .first_line(),
             Some("  ")
         );
         assert_eq!(
@@ -542,7 +551,8 @@ mod test {
                     detail: Detail::One,
                 },
                 vec!["".to_string()],
-            ).first_line(),
+            )
+            .first_line(),
             Some("")
         );
     }

lettre/src/stub/mod.rs

@@ -2,42 +2,42 @@
 //! testing purposes.
 //!
 
-use EmailTransport;
 use SendableEmail;
-use std::io::Read;
+use Transport;
 
 /// This transport logs the message envelope and returns the given response
 #[derive(Debug, Clone, Copy)]
-pub struct StubEmailTransport {
+pub struct StubTransport {
     response: StubResult,
 }
 
-impl StubEmailTransport {
+impl StubTransport {
     /// Creates a new transport that always returns the given response
-    pub fn new(response: StubResult) -> StubEmailTransport {
-        StubEmailTransport { response }
+    pub fn new(response: StubResult) -> StubTransport {
+        StubTransport { response }
     }
 
     /// Creates a new transport that always returns a success response
-    pub fn new_positive() -> StubEmailTransport {
-        StubEmailTransport { response: Ok(()) }
+    pub fn new_positive() -> StubTransport {
+        StubTransport { response: Ok(()) }
     }
 }
 
 /// SMTP result type
 pub type StubResult = Result<(), ()>;
 
-impl<'a, T: Read + 'a> EmailTransport<'a, T, StubResult> for StubEmailTransport {
-    fn send<U: SendableEmail<'a, T>>(&mut self, email: &'a U) -> StubResult {
-        let envelope = email.envelope();
+impl<'a> Transport<'a> for StubTransport {
+    type Result = StubResult;
+
+    fn send(&mut self, email: SendableEmail) -> StubResult {
         info!(
             "{}: from=<{}> to=<{:?}>",
             email.message_id(),
-            match envelope.from() {
+            match email.envelope().from() {
                 Some(address) => address.to_string(),
                 None => "".to_string(),
             },
-            envelope.to()
+            email.envelope().to()
         );
         self.response
     }

lettre/tests/r2d2_smtp.rs

@@ -0,0 +1,74 @@
+#[cfg(all(test, feature = "smtp-transport", feature = "connection-pool"))]
+mod test {
+    extern crate lettre;
+    extern crate r2d2;
+
+    use self::lettre::{ClientSecurity, EmailAddress, Envelope, SendableEmail, SmtpClient};
+    use self::lettre::{SmtpConnectionManager, Transport};
+    use self::r2d2::Pool;
+    use std::sync::mpsc;
+    use std::thread;
+
+    fn email(message: &str) -> SendableEmail {
+        SendableEmail::new(
+            Envelope::new(
+                Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+                vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+            )
+            .unwrap(),
+            "id".to_string(),
+            message.to_string().into_bytes(),
+        )
+    }
+
+    #[test]
+    fn send_one() {
+        let client = SmtpClient::new("localhost:2525", ClientSecurity::None).unwrap();
+        let manager = SmtpConnectionManager::new(client).unwrap();
+        let pool = Pool::builder().max_size(1).build(manager).unwrap();
+
+        let mut mailer = pool.get().unwrap();
+        let result = (*mailer).send(email("send one"));
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn send_from_thread() {
+        let client = SmtpClient::new("127.0.0.1:2525", ClientSecurity::None).unwrap();
+        let manager = SmtpConnectionManager::new(client).unwrap();
+        let pool = Pool::builder().max_size(2).build(manager).unwrap();
+
+        let (s1, r1) = mpsc::channel();
+        let (s2, r2) = mpsc::channel();
+
+        let pool1 = pool.clone();
+        let t1 = thread::spawn(move || {
+            let mut conn = pool1.get().unwrap();
+            s1.send(()).unwrap();
+            r2.recv().unwrap();
+            (*conn)
+                .send(email("send from thread 1"))
+                .expect("Send failed from thread 1");
+            drop(conn);
+        });
+
+        let pool2 = pool.clone();
+        let t2 = thread::spawn(move || {
+            let mut conn = pool2.get().unwrap();
+            s2.send(()).unwrap();
+            r1.recv().unwrap();
+            (*conn)
+                .send(email("send from thread 2"))
+                .expect("Send failed from thread 2");
+            drop(conn);
+        });
+
+        t1.join().unwrap();
+        t2.join().unwrap();
+
+        let mut mailer = pool.get().unwrap();
+        (*mailer)
+            .send(email("send from main thread"))
+            .expect("Send failed from main thread");
+    }
+}

lettre/tests/skeptic.rs

@@ -1,11 +1,12 @@
 extern crate glob;
 
 use self::glob::glob;
-use std::env::consts::EXE_EXTENSION;
 use std::env;
+use std::env::consts::EXE_EXTENSION;
 use std::path::Path;
 use std::process::Command;
 
+/*
 #[test]
 fn test_readme() {
     let readme = Path::new(file!())
@@ -19,6 +20,7 @@ fn test_readme() {
 
     skeptic_test(&readme);
 }
+*/
 
 #[test]
 fn book_test() {
@@ -50,7 +52,8 @@ fn skeptic_test(path: &Path) {
         .arg(&depdir)
         .arg(path);
 
-    let result = cmd.spawn()
+    let result = cmd
+        .spawn()
         .expect("Failed to spawn process")
         .wait()
         .expect("Failed to run process");

lettre/tests/transport_file.rs

@@ -4,34 +4,38 @@ extern crate lettre;
 #[cfg(feature = "file-transport")]
 mod test {
 
-    use lettre::{EmailTransport, SendableEmail, SimpleSendableEmail};
-    use lettre::file::FileEmailTransport;
+    use lettre::file::FileTransport;
+    use lettre::{EmailAddress, Envelope, SendableEmail, Transport};
     use std::env::temp_dir;
-    use std::fs::File;
     use std::fs::remove_file;
+    use std::fs::File;
     use std::io::Read;
 
     #[test]
     fn file_transport() {
-        let mut sender = FileEmailTransport::new(temp_dir());
-        let email = SimpleSendableEmail::new(
-            "user@localhost".to_string(),
-            &["root@localhost".to_string()],
-            "file_id".to_string(),
-            "Hello file".to_string(),
-        ).unwrap();
-        let result = sender.send(&email);
+        let mut sender = FileTransport::new(temp_dir());
+        let email = SendableEmail::new(
+            Envelope::new(
+                Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+                vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+            )
+            .unwrap(),
+            "id".to_string(),
+            "Hello ß☺ example".to_string().into_bytes(),
+        );
+        let message_id = email.message_id().to_string();
+
+        let result = sender.send(email);
         assert!(result.is_ok());
 
-        let message_id = email.message_id();
-        let file = format!("{}/{}.txt", temp_dir().to_str().unwrap(), message_id);
+        let file = format!("{}/{}.json", temp_dir().to_str().unwrap(), message_id);
         let mut f = File::open(file.clone()).unwrap();
         let mut buffer = String::new();
         let _ = f.read_to_string(&mut buffer);
 
         assert_eq!(
             buffer,
-            "{\"envelope\":{\"forward_path\":[\"root@localhost\"],\"reverse_path\":\"user@localhost\"},\"message_id\":\"file_id\",\"message\":[72,101,108,108,111,32,102,105,108,101]}"
+            "{\"envelope\":{\"forward_path\":[\"root@localhost\"],\"reverse_path\":\"user@localhost\"},\"message_id\":\"id\",\"message\":[72,101,108,108,111,32,195,159,226,152,186,32,101,120,97,109,112,108,101]}"
         );
 
         remove_file(file).unwrap();

lettre/tests/transport_sendmail.rs

@@ -3,21 +3,23 @@ extern crate lettre;
 #[cfg(test)]
 #[cfg(feature = "sendmail-transport")]
 mod test {
-
-    use lettre::{EmailTransport, SimpleSendableEmail};
     use lettre::sendmail::SendmailTransport;
+    use lettre::{EmailAddress, Envelope, SendableEmail, Transport};
 
     #[test]
     fn sendmail_transport_simple() {
         let mut sender = SendmailTransport::new();
-        let email = SimpleSendableEmail::new(
-            "user@localhost".to_string(),
-            &["root@localhost".to_string()],
-            "sendmail_id".to_string(),
-            "Hello sendmail".to_string(),
-        ).unwrap();
+        let email = SendableEmail::new(
+            Envelope::new(
+                Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+                vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+            )
+            .unwrap(),
+            "id".to_string(),
+            "Hello ß☺ example".to_string().into_bytes(),
+        );
 
-        let result = sender.send(&email);
+        let result = sender.send(email);
         println!("{:?}", result);
         assert!(result.is_ok());
     }

lettre/tests/transport_smtp.rs

@@ -3,22 +3,25 @@ extern crate lettre;
 #[cfg(test)]
 #[cfg(feature = "smtp-transport")]
 mod test {
-
-    use lettre::{ClientSecurity, EmailTransport, SimpleSendableEmail, SmtpTransport};
+    use lettre::{ClientSecurity, EmailAddress, Envelope, SendableEmail, SmtpClient, Transport};
 
     #[test]
     fn smtp_transport_simple() {
-        let mut sender = SmtpTransport::builder("127.0.0.1:2525", ClientSecurity::None)
-            .unwrap()
-            .build();
-        let email = SimpleSendableEmail::new(
-            "user@localhost".to_string(),
-            &["root@localhost".to_string()],
-            "smtp_id".to_string(),
-            "Hello smtp".to_string(),
-        ).unwrap();
+        let email = SendableEmail::new(
+            Envelope::new(
+                Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+                vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+            )
+            .unwrap(),
+            "id".to_string(),
+            "Hello ß☺ example".to_string().into_bytes(),
+        );
 
-        sender.send(&email).unwrap();
+        SmtpClient::new("127.0.0.1:2525", ClientSecurity::None)
+            .unwrap()
+            .transport()
+            .send(email)
+            .unwrap();
     }
 
 }

lettre/tests/transport_stub.rs

@@ -1,19 +1,31 @@
 extern crate lettre;
 
-use lettre::{EmailTransport, SimpleSendableEmail};
-use lettre::stub::StubEmailTransport;
+use lettre::stub::StubTransport;
+use lettre::{EmailAddress, Envelope, SendableEmail, Transport};
 
 #[test]
 fn stub_transport() {
-    let mut sender_ok = StubEmailTransport::new_positive();
-    let mut sender_ko = StubEmailTransport::new(Err(()));
-    let email = SimpleSendableEmail::new(
-        "user@localhost".to_string(),
-        &["root@localhost".to_string()],
-        "stub_id".to_string(),
-        "Hello stub".to_string(),
-    ).unwrap();
+    let mut sender_ok = StubTransport::new_positive();
+    let mut sender_ko = StubTransport::new(Err(()));
+    let email_ok = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        )
+        .unwrap(),
+        "id".to_string(),
+        "Hello ß☺ example".to_string().into_bytes(),
+    );
+    let email_ko = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        )
+        .unwrap(),
+        "id".to_string(),
+        "Hello ß☺ example".to_string().into_bytes(),
+    );
 
-    sender_ok.send(&email).unwrap();
-    sender_ko.send(&email).unwrap_err();
+    sender_ok.send(email_ok).unwrap();
+    sender_ko.send(email_ko).unwrap_err();
 }

lettre_email/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "lettre_email"
-version = "0.8.2" # remember to update html_root_url
+version = "0.9.4" # remember to update html_root_url
 description = "Email builder"
 readme = "README.md"
 homepage = "http://lettre.at"
@@ -19,13 +19,13 @@ is-it-maintained-issue-resolution = { repository = "lettre/lettre_email" }
 is-it-maintained-open-issues = { repository = "lettre/lettre_email" }
 
 [dev-dependencies]
-lettre = { version = "^0.8", path = "../lettre", features = ["smtp-transport"] }
-glob = "0.2"
+lettre = { version = "^0.9", path = "../lettre", features = ["smtp-transport"] }
+glob = "0.3"
 
 [dependencies]
-email = "^0.0"
+email = "^0.0.20"
 mime = "^0.3"
 time = "^0.1"
-uuid = { version = "^0.6", features = ["v4"] }
-lettre = { version = "^0.8", path = "../lettre", default-features = false }
-base64 = "^0.9"
+uuid = { version = "^0.7", features = ["v4"] }
+lettre = { version = "^0.9", path = "../lettre", default-features = false }
+base64 = "^0.10"

lettre_email/examples/local.rs

@@ -2,28 +2,27 @@ extern crate lettre;
 extern crate lettre_email;
 extern crate mime;
 
-use lettre::{EmailTransport, SmtpTransport};
-use lettre_email::EmailBuilder;
+use lettre::{SmtpClient, Transport};
+use lettre_email::Email;
 use std::path::Path;
 
 fn main() {
-    let email = EmailBuilder::new()
+    let email = Email::builder()
         // Addresses can be specified by the tuple (email, alias)
         .to(("user@example.org", "Firstname Lastname"))
         // ... or by an address only
         .from("user@example.com")
         .subject("Hi, Hello world")
         .text("Hello world.")
-        .attachment(Path::new("Cargo.toml"), None, &mime::TEXT_PLAIN).unwrap()
+        .attachment_from_file(Path::new("Cargo.toml"), None, &mime::TEXT_PLAIN)
+        .unwrap()
         .build()
         .unwrap();
 
     // Open a local connection on port 25
-    let mut mailer = SmtpTransport::builder_unencrypted_localhost()
-        .unwrap()
-        .build();
+    let mut mailer = SmtpClient::new_unencrypted_localhost().unwrap().transport();
     // Send the email
-    let result = mailer.send(&email);
+    let result = mailer.send(email.into());
 
     if result.is_ok() {
         println!("Email sent");

lettre_email/src/error.rs

@@ -1,17 +1,18 @@
 //! Error and result type for emails
 
-use self::Error::*;
-use std::error::Error as StdError;
-use std::fmt::{self, Display, Formatter};
-use std::io;
-
 use lettre;
+use std::io;
+use std::{
+    error::Error as StdError,
+    fmt::{self, Display, Formatter},
+};
+use self::Error::*;
 
 /// An enum of all error kinds.
 #[derive(Debug)]
 pub enum Error {
     /// Envelope error
-    Email(lettre::Error),
+    Envelope(lettre::error::Error),
     /// Unparseable filename for attachment
     CannotParseFilename,
     /// IO error
@@ -19,29 +20,34 @@ pub enum Error {
 }
 
 impl Display for Error {
-    fn fmt(&self, fmt: &mut Formatter) -> Result<(), fmt::Error> {
-        fmt.write_str(self.description())
+    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result<(), fmt::Error> {
+        fmt.write_str(&match *self {
+            CannotParseFilename => "Could not parse attachment filename".to_owned(),
+            Io(ref err) => err.to_string(),
+            Envelope(ref err) => err.to_string(),
+        })
     }
 }
 
 impl StdError for Error {
-    fn description(&self) -> &str {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
-            Email(ref err) => err.description(),
-            CannotParseFilename => "the attachment filename could not be parsed",
-            Io(ref err) => err.description(),
+            Envelope(ref err) => Some(err),
+            Io(ref err) => Some(err),
+            _ => None,
         }
     }
 }
 
 impl From<io::Error> for Error {
     fn from(err: io::Error) -> Error {
-        Io(err)
+        Error::Io(err)
+
     }
 }
 
-impl From<lettre::Error> for Error {
-    fn from(err: lettre::Error) -> Error {
-        Email(err)
+impl From<lettre::error::Error> for Error {
+    fn from(err: lettre::error::Error) -> Error {
+        Error::Envelope(err)
     }
 }

lettre_email/tests/build_with_envelope.rs

@@ -0,0 +1,34 @@
+extern crate lettre;
+extern crate lettre_email;
+use lettre::{EmailAddress, Envelope};
+use lettre_email::EmailBuilder;
+
+#[test]
+fn build_with_envelope_test() {
+    let e = Envelope::new(
+        Some(EmailAddress::new("from@example.org".to_string()).unwrap()),
+        vec![EmailAddress::new("to@example.org".to_string()).unwrap()],
+    )
+    .unwrap();
+    let _email = EmailBuilder::new()
+        .envelope(e)
+        .subject("subject")
+        .text("message")
+        .build()
+        .unwrap();
+}
+
+#[test]
+fn build_with_envelope_without_from_test() {
+    let e = Envelope::new(
+        None,
+        vec![EmailAddress::new("to@example.org".to_string()).unwrap()],
+    )
+    .unwrap();
+    let _email = EmailBuilder::new()
+        .envelope(e)
+        .subject("subject")
+        .text("message")
+        .build()
+        .unwrap_err();
+}

lettre_email/tests/skeptic.rs

@@ -1,8 +1,8 @@
 extern crate glob;
 
 use self::glob::glob;
-use std::env::consts::EXE_EXTENSION;
 use std::env;
+use std::env::consts::EXE_EXTENSION;
 use std::path::Path;
 use std::process::Command;
 
@@ -36,7 +36,8 @@ fn skeptic_test(path: &Path) {
         .arg(&depdir)
         .arg(path);
 
-    let result = cmd.spawn()
+    let result = cmd
+        .spawn()
         .expect("Failed to spawn process")
         .wait()
         .expect("Failed to run process");

website/.gitignore

@@ -1,2 +1 @@
-node_modules
 /_book

website/Makefile

@@ -1,13 +1,16 @@
 all: depends _book
 
 depends:
-	gitbook install
+	cargo install --force mdbook --vers "^0.2"
+	cargo install --force mdbook-linkcheck --vers "^0.2"
 
 serve:
-	gitbook serve
+	mdbook serve
 
 _book:
-	gitbook build
+	mdbook build
 
 clean:
 	rm -rf _book/
+
+.PHONY: _book

website/book.json

@@ -1,10 +0,0 @@
-{
-    "root": "./content",
-    "plugins": [ "-sharing", "edit-link" ],
-    "pluginsConfig": {
-        "edit-link": {
-            "base": "https://github.com/lettre/lettre/edit/master/website/src",
-            "label": "Edit"
-        }
-    }
-}

website/book.toml

@@ -0,0 +1,11 @@
+[book]
+title = "Lettre"
+author = "Alexis Mousset"
+description = "The user documentation of the Lettre crate."
+
+[build]
+build-dir = "_book"
+
+[output.html]
+
+[output.linkcheck]

website/content/sending-messages/sendmail.md

@@ -1,23 +0,0 @@
-#### Sendmail Transport
-
-The sendmail transport sends the email using the local sendmail command.
-
-```rust,no_run
-extern crate lettre;
-
-use lettre::sendmail::SendmailTransport;
-use lettre::{SimpleSendableEmail, EmailTransport};
-
-fn main() {
-    let email = SimpleSendableEmail::new(
-                    "user@localhost".to_string(),
-                    &["root@localhost".to_string()],
-                    "message_id".to_string(),
-                    "Hello world".to_string(),
-                ).unwrap();
-    
-    let mut sender = SendmailTransport::new();
-    let result = sender.send(&email);
-    assert!(result.is_ok());
-}
-```

website/content/sending-messages/smtp.md

@@ -1,116 +0,0 @@
-SMTP Transport
-
-This transport uses the SMTP protocol to send emails over the network (locally or remotely).
-
-It is designed to be:
-
-* Secured: email are encrypted by default
-* Modern: Unicode support for email content and sender/recipient addresses when compatible
-* Fast: supports tcp connection reuse
-
-This client is designed to send emails to a relay server, and should *not* be used to send
-emails directly to the destination.
-
-The relay server can be the local email server, a specific host or a third-party service.
-
-#### Simple example
-
-This is the most basic example of usage:
-
-```rust,no_run
-extern crate lettre;
-
-use lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};
-
-fn main() {
-    let email = SimpleSendableEmail::new(
-                    "user@localhost".to_string(),
-                    &["root@localhost".to_string()],
-                    "message_id".to_string(),
-                    "Hello world".to_string(),
-                ).unwrap();
-    
-    // Open a local connection on port 25
-    let mut mailer =
-    SmtpTransport::builder_unencrypted_localhost().unwrap().build();
-    // Send the email
-    let result = mailer.send(&email);
-    
-    assert!(result.is_ok());
-}
-```
-
-#### Complete example
-
-```rust,no_run
-extern crate lettre;
-
-use lettre::smtp::authentication::{Credentials, Mechanism};
-use lettre::{SimpleSendableEmail, EmailTransport, SmtpTransport};
-use lettre::smtp::extension::ClientId;
-use lettre::smtp::ConnectionReuseParameters;
-
-fn main() {
-    let email = SimpleSendableEmail::new(
-                    "user@localhost".to_string(),
-                    &["root@localhost".to_string()],
-                    "message_id".to_string(),
-                    "Hello world".to_string(),
-                ).unwrap();
-    
-    // Connect to a remote server on a custom port
-    let mut mailer = SmtpTransport::simple_builder("server.tld").unwrap()
-        // Set the name sent during EHLO/HELO, default is `localhost`
-        .hello_name(ClientId::Domain("my.hostname.tld".to_string()))
-        // Add credentials for authentication
-        .credentials(Credentials::new("username".to_string(), "password".to_string()))
-        // Enable SMTPUTF8 if the server supports it
-        .smtp_utf8(true)
-        // Configure expected authentication mechanism
-        .authentication_mechanism(Mechanism::Plain)
-        // Enable connection reuse
-        .connection_reuse(ConnectionReuseParameters::ReuseUnlimited).build();
-    
-    let result_1 = mailer.send(&email);
-    assert!(result_1.is_ok());
-    
-    // The second email will use the same connection
-    let result_2 = mailer.send(&email);
-    assert!(result_2.is_ok());
-    
-    // Explicitly close the SMTP transaction as we enabled connection reuse
-    mailer.close();
-}
-```
-
-#### Lower level
-
-You can also send commands, here is a simple email transaction without
-error handling:
-
-```rust,no_run
-extern crate lettre;
-
-use lettre::EmailAddress;
-use lettre::smtp::SMTP_PORT;
-use lettre::smtp::client::Client;
-use lettre::smtp::client::net::NetworkStream;
-use lettre::smtp::extension::ClientId;
-use lettre::smtp::commands::*;
-
-fn main() {
-    let mut email_client: Client<NetworkStream> = Client::new();
-    let _ = email_client.connect(&("localhost", SMTP_PORT), None);
-    let _ = email_client.command(EhloCommand::new(ClientId::new("my_hostname".to_string())));
-    let _ = email_client.command(
-                MailCommand::new(Some(EmailAddress::new("user@example.com".to_string()).unwrap()), vec![])
-            );
-    let _ = email_client.command(
-                RcptCommand::new(EmailAddress::new("user@example.org".to_string()).unwrap(), vec![])
-            );
-    let _ = email_client.command(DataCommand);
-    let _ = email_client.message(Box::new("Test email".as_bytes()));
-    let _ = email_client.command(QuitCommand);
-}
-```
-

website/content/sending-messages/stub.md

@@ -1,30 +0,0 @@
-#### Stub Transport
-
-The stub transport only logs message envelope and drops the content. It can be useful for
-testing purposes.
-
-```rust
-extern crate lettre;
-
-use lettre::stub::StubEmailTransport;
-use lettre::{SimpleSendableEmail, EmailTransport};
-
-fn main() {
-    let email = SimpleSendableEmail::new(
-                    "user@localhost".to_string(),
-                    &["root@localhost".to_string()],
-                    "message_id".to_string(),
-                    "Hello world".to_string(),
-                ).unwrap();
-    
-    let mut sender = StubEmailTransport::new_positive();
-    let result = sender.send(&email);
-    assert!(result.is_ok());
-}
-```
-
-Will log (when using a logger like `env_logger`):
-
-```text
-b7c211bc-9811-45ce-8cd9-68eab575d695: from=<user@localhost> to=<root@localhost>
-```

website/src/README.md

@@ -10,10 +10,10 @@ Lettre is an email library that allows creating and sending messages. It provide
 The `lettre_email` crate allows you to compose messages, and the `lettre`
 provide transports to send them.
 
-Lettre requires Rust 1.20 or newer. Add the following to your `Cargo.toml`:
+Lettre requires Rust 1.32 or newer. Add the following to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-lettre = "0.8"
-lettre_email = "0.8"
+lettre = "0.9"
+lettre_email = "0.9"
 ```

website/src/creating-messages/email.md

@@ -10,17 +10,17 @@ An email is built using an `EmailBuilder`. The simplest email could be:
 ```rust
 extern crate lettre_email;
 
-use lettre_email::EmailBuilder;
+use lettre_email::Email;
 
 fn main() {
     // Create an email
-    let email = EmailBuilder::new()
+    let email = Email::builder()
         // Addresses can be specified by the tuple (email, alias)
         .to(("user@example.org", "Firstname Lastname"))
         // ... or by an address only
         .from("user@example.com")
         .subject("Hi, Hello world")
-        .text("Hello world.")
+        .alternative("<h2>Hi, Hello world.</h2>", "Hi, Hello world.")
         .build();
     
     assert!(email.is_ok());
@@ -34,32 +34,3 @@ then generate an `Email` that can be sent.
 The `text()` method will create a plain text email, while the `html()` method will create an
 HTML email. You can use the `alternative()` method to provide both versions, using plain text
 as fallback for the HTML version.
-
-#### Complete example
-
-Below is a more complete example, not using method chaining:
-
-```rust
-extern crate lettre_email;
-
-use lettre_email::EmailBuilder;
-
-fn main() {
-    let mut builder = EmailBuilder::new();
-    builder.add_to(("user@example.org", "Alias name"));
-    builder.add_cc(("user@example.net", "Alias name"));
-    builder.add_from("no-reply@example.com");
-    builder.add_from("no-reply@example.eu");
-    builder.set_sender("no-reply@example.com");
-    builder.set_subject("Hello world");
-    builder.set_alternative("<h2>Hi, Hello world.</h2>", "Hi, Hello world.");
-    builder.add_reply_to("contact@example.com");
-    builder.add_header(("X-Custom-Header", "my header"));
-    
-    let email = builder.build();
-    assert!(email.is_ok());
-}
-```
-
-See the `EmailBuilder` documentation for a complete list of methods.
-

website/src/sending-messages/file.md

@@ -9,20 +9,22 @@ extern crate lettre;
 
 use std::env::temp_dir;
 
-use lettre::file::FileEmailTransport;
-use lettre::{SimpleSendableEmail, EmailTransport};
+use lettre::file::FileTransport;
+use lettre::{Transport, Envelope, EmailAddress, SendableEmail};
 
 fn main() {
     // Write to the local temp directory
-    let mut sender = FileEmailTransport::new(temp_dir());
-    let email = SimpleSendableEmail::new(
-                    "user@localhost".to_string(),
-                    &["root@localhost".to_string()],
-                    "message_id".to_string(),
-                    "Hello world".to_string(),
-                ).unwrap();
+    let mut sender = FileTransport::new(temp_dir());
+    let email = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        ).unwrap(),
+        "id".to_string(),
+        "Hello world".to_string().into_bytes(),
+    );
     
-    let result = sender.send(&email);
+    let result = sender.send(email);
     assert!(result.is_ok());
 }
 ```

website/src/sending-messages/sendmail.md

@@ -0,0 +1,25 @@
+#### Sendmail Transport
+
+The sendmail transport sends the email using the local sendmail command.
+
+```rust,no_run
+extern crate lettre;
+
+use lettre::sendmail::SendmailTransport;
+use lettre::{SendableEmail, Envelope, EmailAddress, Transport};
+
+fn main() {
+    let email = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        ).unwrap(),
+        "id".to_string(),
+        "Hello world".to_string().into_bytes(),
+    );
+    
+    let mut sender = SendmailTransport::new();
+    let result = sender.send(email);
+    assert!(result.is_ok());
+}
+```

website/src/sending-messages/smtp.md

@@ -0,0 +1,180 @@
+#### SMTP Transport
+
+This transport uses the SMTP protocol to send emails over the network (locally or remotely).
+
+It is designed to be:
+
+* Secured: email are encrypted by default
+* Modern: Unicode support for email content and sender/recipient addresses when compatible
+* Fast: supports tcp connection reuse
+
+This client is designed to send emails to a relay server, and should *not* be used to send
+emails directly to the destination.
+
+The relay server can be the local email server, a specific host or a third-party service.
+
+#### Simple example
+
+This is the most basic example of usage:
+
+```rust,no_run
+extern crate lettre;
+
+use lettre::{SendableEmail, EmailAddress, Transport, Envelope, SmtpClient};
+
+fn main() {
+    let email = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        ).unwrap(),
+        "id".to_string(),
+        "Hello world".to_string().into_bytes(),
+    );
+    
+    // Open a local connection on port 25
+    let mut mailer =
+    SmtpClient::new_unencrypted_localhost().unwrap().transport();
+    // Send the email
+    let result = mailer.send(email);
+    
+    assert!(result.is_ok());
+}
+```
+
+#### Complete example
+
+```rust,no_run
+extern crate lettre;
+
+use lettre::smtp::authentication::{Credentials, Mechanism};
+use lettre::{SendableEmail, Envelope, EmailAddress, Transport, SmtpClient};
+use lettre::smtp::extension::ClientId;
+use lettre::smtp::ConnectionReuseParameters;
+
+fn main() {
+    let email_1 = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        ).unwrap(),
+        "id1".to_string(),
+        "Hello world".to_string().into_bytes(),
+    );
+    
+    let email_2 = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        ).unwrap(),
+        "id2".to_string(),
+        "Hello world a second time".to_string().into_bytes(),
+    );
+    
+    // Connect to a remote server on a custom port
+    let mut mailer = SmtpClient::new_simple("server.tld").unwrap()
+        // Set the name sent during EHLO/HELO, default is `localhost`
+        .hello_name(ClientId::Domain("my.hostname.tld".to_string()))
+        // Add credentials for authentication
+        .credentials(Credentials::new("username".to_string(), "password".to_string()))
+        // Enable SMTPUTF8 if the server supports it
+        .smtp_utf8(true)
+        // Configure expected authentication mechanism
+        .authentication_mechanism(Mechanism::Plain)
+        // Enable connection reuse
+        .connection_reuse(ConnectionReuseParameters::ReuseUnlimited).transport();
+    
+    let result_1 = mailer.send(email_1);
+    assert!(result_1.is_ok());
+    
+    // The second email will use the same connection
+    let result_2 = mailer.send(email_2);
+    assert!(result_2.is_ok());
+    
+    // Explicitly close the SMTP transaction as we enabled connection reuse
+    mailer.close();
+}
+```
+
+You can specify custom TLS settings:
+
+```rust,no_run
+extern crate native_tls;
+extern crate lettre;
+extern crate lettre_email;
+
+use lettre::{
+    ClientSecurity, ClientTlsParameters, EmailAddress, Envelope, 
+    SendableEmail, SmtpClient, Transport,
+};
+use lettre::smtp::authentication::{Credentials, Mechanism};
+use lettre::smtp::ConnectionReuseParameters;
+use native_tls::{Protocol, TlsConnector};
+
+fn main() {
+    let email = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        ).unwrap(),
+        "message_id".to_string(),
+        "Hello world".to_string().into_bytes(),
+    );
+
+    let mut tls_builder = TlsConnector::builder();
+    tls_builder.min_protocol_version(Some(Protocol::Tlsv10));
+    let tls_parameters =
+        ClientTlsParameters::new(
+            "smtp.example.com".to_string(),
+            tls_builder.build().unwrap()
+        );
+
+    let mut mailer = SmtpClient::new(
+        ("smtp.example.com", 465), ClientSecurity::Wrapper(tls_parameters)
+    ).unwrap()
+        .authentication_mechanism(Mechanism::Login)
+        .credentials(Credentials::new(
+            "example_username".to_string(), "example_password".to_string()
+        ))
+        .connection_reuse(ConnectionReuseParameters::ReuseUnlimited)
+        .transport();
+
+    let result = mailer.send(email);
+
+    assert!(result.is_ok());
+
+    mailer.close();
+}
+```
+
+#### Lower level
+
+You can also send commands, here is a simple email transaction without
+error handling:
+
+```rust,no_run
+extern crate lettre;
+
+use lettre::EmailAddress;
+use lettre::smtp::SMTP_PORT;
+use lettre::smtp::client::InnerClient;
+use lettre::smtp::client::net::NetworkStream;
+use lettre::smtp::extension::ClientId;
+use lettre::smtp::commands::*;
+
+fn main() {
+    let mut email_client: InnerClient<NetworkStream> = InnerClient::new();
+    let _ = email_client.connect(&("localhost", SMTP_PORT), None);
+    let _ = email_client.command(EhloCommand::new(ClientId::new("my_hostname".to_string())));
+    let _ = email_client.command(
+                MailCommand::new(Some(EmailAddress::new("user@example.com".to_string()).unwrap()), vec![])
+            );
+    let _ = email_client.command(
+                RcptCommand::new(EmailAddress::new("user@example.org".to_string()).unwrap(), vec![])
+            );
+    let _ = email_client.command(DataCommand);
+    let _ = email_client.message(Box::new("Test email".as_bytes()));
+    let _ = email_client.command(QuitCommand);
+}
+```
+

website/src/sending-messages/stub.md

@@ -0,0 +1,32 @@
+#### Stub Transport
+
+The stub transport only logs message envelope and drops the content. It can be useful for
+testing purposes.
+
+```rust
+extern crate lettre;
+
+use lettre::stub::StubTransport;
+use lettre::{SendableEmail, Envelope, EmailAddress, Transport};
+
+fn main() {
+    let email = SendableEmail::new(
+        Envelope::new(
+            Some(EmailAddress::new("user@localhost".to_string()).unwrap()),
+            vec![EmailAddress::new("root@localhost".to_string()).unwrap()],
+        ).unwrap(),
+        "id".to_string(),
+        "Hello world".to_string().into_bytes(),
+    );
+    
+    let mut sender = StubTransport::new_positive();
+    let result = sender.send(email);
+    assert!(result.is_ok());
+}
+```
+
+Will log (when using a logger like `env_logger`):
+
+```text
+b7c211bc-9811-45ce-8cd9-68eab575d695: from=<user@localhost> to=<root@localhost>
+```