msmtp
In the default mode, it transmits a mail to an SMTP server (for example at a free mail provider) which takes care of further delivery. 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/SSL support including client certificates Many authentication methods Support for Internationalized Domain Names (IDN) Fast SMTP implementation using command pipelining DSN (Delivery Status Notification) support SOCKS proxy support
