msmtp -- SMTP plugin for MUAs

This is a simple program that works as an "SMTP plugin" for Mutt and probably 
other MUAs (mail user agents).  msmtp forwards mails to an SMTP server (for 
example at a free mail provider) which does the delivery.  

Features include:
    * SMTP AUTH methods PLAIN, LOGIN and CRAM-MD5
    * TLS encrypted connections
    * IPv6 support
    * robustness
    * detailed error messages (including the full answer of the SMTP server) 
      if something goes wrong
    * sendmail compatible exit codes (which most MUAs understand).

Simply tell your MUA to call msmtp instead of /usr/sbin/sendmail 

WWW: http://msmtp.sourceforge.net/