msmtp is an SMTP client.

In the default mode, it transmits a mail to an SMTP server.

To use this program with your mail user agent (MUA), create a configuration file with your mail account(s) and tell your MUA to call msmtp instead of /usr/sbin/sendmail.

Features include:

• Sendmail compatible interface (command line options and exit codes)
• Support for multiple accounts
• TLS support including client certificates
• Support for Internationalized Domain Names (IDN)
• Many authentication methods
• Fast SMTP implementation using command pipelining
• DSN (Delivery Status Notification) support
• SOCKS proxy support

msmtp runs on a wide variety of platforms. It needs little more than an ANSI C compiler and Berkeley-style sockets. It does not require any additional libraries, but it can use the following to enhance its feature set:

• GnuTLS. The GnuTLS library provides TLS support. Alternatively, libtls from the LibreSSL project can be used.
• GNU SASL. Using the GNU SASL library adds support for some additional authentication methods, including SCRAM-* and GSSAPI.
• GNU libidn2. On modern Linux systems with recent glibc and GnuTLS libraries, msmtp has automatic support for Internationalized Domain Names (IDN). On other systems, IDN support is available via libidn2.

The homepage of this program is https://marlam.de/msmtp.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (see the file COPYING) as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.