Postfix was created in 1998 by Wietse Venema at IBM Research as a secure, modular alternative to Sendmail, which dominated email delivery but was notoriously complex and vulnerability-prone. While a clean-room rewrite rather than a code fork, it was designed explicitly to replace Sendmail.
Postfix uses a master daemon that spawns small, specialized programs (smtpd, cleanup, qmgr, local, etc.) each running with minimal privileges. Programs communicate via well-defined protocols over Unix domain sockets or FIFOs. The configuration uses simple key=value lookup tables rather than Sendmail's notoriously complex m4 macros.
By the mid-1990s, Sendmail handled an estimated 80% of the world's email traffic, but its monolithic architecture and long history of security vulnerabilities made it increasingly problematic. Wietse Venema, already famous for co-creating the SATAN network security scanner and TCP Wrapper, began developing an alternative at IBM's Thomas J. Watson Research Center in 1997.
The software was initially released in December 1998 under the name 'VMailer' through IBM's AlphaWorks website, then briefly called 'IBM Secure Mailer' before trademark issues led to the final name 'Postfix' -- a portmanteau of 'post' (mail) and 'bugfix.' It was released under the IBM Public License 1.0.
Postfix was architecturally revolutionary compared to Sendmail: instead of a single monolithic setuid-root binary, it used a collection of small, single-purpose programs running with minimal privileges in a chroot environment, communicating through well-defined interfaces. This design made it both more secure and easier to understand. Postfix adopted Sendmail-compatible interfaces (sendmail command, .forward files) to ease migration.
By 2020, Sendmail's market share had dropped from 80% to approximately 4%, with Postfix and Exim capturing the majority of deployments.
Development begins at IBM Watson Research Center
Released as VMailer/IBM Secure Mailer via AlphaWorks
Renamed to Postfix due to trademark issues
Postfix 2.0 released with major feature expansion
Postfix fundamentally changed how mail servers were designed and deployed, proving that security-first architecture could also be performant and user-friendly. It contributed to the decline of Sendmail from 80% market share to under 5%. Postfix's modular, least-privilege architecture became a model for secure systems design beyond email.