Postfix
Postfix is an open source mail transfer agent (MTA), a computer program for the routing and delivery of email, that is intended as a fast, easy to administer and secure alternative to the widely-used Sendmail. Formerly known as VMailer and IBM Secure Mailer, it was originally written by Wietse Venema during a stay at the IBM T. J. Watson Research, and continues to be developed actively until today.Postfix is also the default MTA in Trustix Secure Linux. The main reason Postfix has not seen more widespread use is because it is not licensed under the GPL or BSD license. In fact the official website includes no information about its licensing scheme (Oct. 2003) in recognition of this weakness.
