esmtp is a user configurable relay-only Mail Transfer Agent
(MTA) with a sendmail compatible syntax. It's based on libESMTP
supporting the AUTH (including the CRAM-MD5 and NTLM SASL
mechanisms) and the StartTLS SMTP extensions.

These are the esmtp features:

    * fully sendmail command line compatible,
    * supports the AUTH SMTP extension, with the CRAM-MD5 and
    * NTLM SASL mechanisms,
    * support the StartTLS SMTP extension,
    * requires no administration privileges,
    * individual user configuration,
    * does not receive mail, expand aliases or manage a queue.
 
WWW: http://esmtp.sourceforge.net