What is Postfix? It is Wietse Venema’s mail server. It was originally developed by IBM Research as an alternative to Sendmail. Wietse Venema continues to support Postfix at Google. Postfix works (or has worked) on AIX and BSD, HPUX, IRIX. LINUX. MacOS X. Solaris. Tru64 UNIX. It requires ANSI C and a POSIX.1 librarian. Postfix aims to be fast, simple to administer, and secure. Although the outside is very Sendmail-ish, the inside is entirely different. Multiple SMTP delivery over the same TLS encrypted connection. This reuses existing tlsproxy(8), scache(8) services. MySQL stored procedure support. Gradual degradation: In many cases, a Postfix daemon will log an error and continue to provide services that are still available instead of terminating with a fatality. Postfix can set an execute bit in a queue file. If this fails, no mail will be delivered.