Msmtp

msmtp is an easy to configure basic email sender client with fairly complete sendmail compatibility.

Installation

A minimal configuration to relay mails through an external mail server coud look like this

⚠︎

Warning: Do not use a plaintext password in production, this is for demonstration only

programs.msmtp = {
  enable = true;
  accounts.default = {
    host = "example.org";
    from = "hello@example.org";
    user = "hello@example.org";
    password = "mypassword123";
  };
};

In this case msmtp will try to deliver mails through the smtp server example.org on port 25. user and password are used for normal plaintext authentication.

This configuration will automatically set msmtp as the default mail delivery client on your system by overwriting the sendmail binary. To test mail delivery issue following command:

# echo -e "Content-Type: text/plain\r\nSubject: Test\r\n\r\nHello World" | sendmail john.doe@mail.com

A mail with the subject Test will be sent to the recipient john.doe@mail.com including the body text Hello World. A Mime-Header is added to the mail content for better compatibility.

Configuration

Further configuration options for msmtp can be found here.

TLS connections

programs.msmtp = {
  enable = true;
  accounts = {
    default = {
      auth = true;
      tls = true;
      # try setting `tls_starttls` to `false` if sendmail hangs
      from = "<from address here>";
      host = "<hostname here>";
      user = "<username here>";
      passwordeval = "cat /secrets/smtp_password.txt";
    };
  };
};

Note that msmtp has no daemon and runs as the invoking user. If using passwordeval, the file must be readable by any user that wishes to send mail.

Aliases

Example:

programs.msmtp.defaults = {
  aliases = "/etc/aliases";
};

environment.etc = {
  "aliases" = {
    text = ''
      root: me@example.com
    '';
    mode = "0644";
  };
};

See also

• msmtp options list