32 releases

0.10.0-rc.3 May 22, 2021
0.10.0-beta.3 Mar 18, 2021
0.10.0-alpha.4 Nov 11, 2020
0.10.0-alpha.1 May 31, 2020
0.5.0 Oct 26, 2015

#6 in Email

Download history 4724/week @ 2021-02-24 4794/week @ 2021-03-03 4809/week @ 2021-03-10 4895/week @ 2021-03-17 4985/week @ 2021-03-24 4662/week @ 2021-03-31 4868/week @ 2021-04-07 4992/week @ 2021-04-14 4631/week @ 2021-04-21 4714/week @ 2021-04-28 5096/week @ 2021-05-05 4479/week @ 2021-05-12 4805/week @ 2021-05-19 5596/week @ 2021-05-26 5155/week @ 2021-06-02 3982/week @ 2021-06-09

20,670 downloads per month
Used in 26 crates (24 directly)

MIT license

7.5K SLoC


A mailer library for Rust

NOTE: this readme refers to the 0.10 version of lettre, which is in release candidate state. Use the v0.9.x branch for the previous stable release.

0.10 is already widely used and is already thought to be more reliable than 0.9, so it should generally be used for new projects.

We'd love to hear your feedback about 0.10 design and APIs before final release! Start a discussion in the repository, whether for feedback or if you need help or advice using or upgrading lettre 0.10.


Lettre provides the following features:

  • Multiple transport methods
  • Unicode support (for email content and addresses)
  • Secure delivery with SMTP using encryption and authentication
  • Easy email builders
  • Async support

Lettre does not provide (for now):

  • Email parsing


This library requires Rust 1.46 or newer. To use this library, add the following to your Cargo.toml:

lettre = "0.10.0-rc.3"
use lettre::transport::smtp::authentication::Credentials;
use lettre::{Message, SmtpTransport, Transport};

let email = Message::builder()
    .from("NoBody <nobody@domain.tld>".parse().unwrap())
    .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
    .to("Hei <hei@domain.tld>".parse().unwrap())
    .subject("Happy new year")
    .body(String::from("Be happy!"))

let creds = Credentials::new("smtp_username".to_string(), "smtp_password".to_string());

// Open a remote connection to gmail
let mailer = SmtpTransport::relay("smtp.gmail.com")

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


The lettre tests require an open mail server listening locally on port 2525 and the sendmail command.

Alternatively only unit tests can be run by doing cargo test --lib.

Code of conduct

Anyone who interacts with Lettre in any space, including but not limited to this GitHub repository, must follow our code of conduct.


This program is distributed under the terms of the MIT license.

The builder comes from emailmessage-rs by Kayo, under MIT license.

See LICENSE for details.


~25K SLoC