Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail.
It is released under the IBM Public License 1.0 which is a free software license. Alternatively, starting with version 3.2.5, it is available under the Eclipse Public License 2.0 at the user's option.
Originally written in 1997 by Wietse Venema at the IBM Thomas J. Watson Research Center in New York, and first released in December 1998, Postfix continues as of 2024[update] to be actively developed by its creator and other contributors. The software is also known by its former names VMailer and IBM Secure Mailer. The name Postfix is a compound of "post" (which is another word for "mail") and "bugfix" (which is for other software that inspired Postfix development).