Postfix review: the free, open-source mail transfer agent that powers much of the internet's email routing. Features, setup notes and alternatives.
Postfix is a free, open-source mail transfer agent that routes and delivers email over SMTP between mail servers. It was written by Wietse Venema at IBM Research and released publicly in December 1998 as a secure, high-performance replacement for Sendmail.
As a pure MTA, Postfix handles mail routing, queuing and delivery, and is typically combined with other components like an IMAP/POP3 server and spam filtering software to form a complete mail server stack. It ships as the default mail server on many Linux distributions.
Postfix uses a modular, multi-process architecture that separates functions like queue management, SMTP delivery and local delivery into distinct, minimally privileged processes, which improves both security and stability compared to monolithic MTA designs.
It supports SMTP authentication, TLS encryption, content filtering hooks, virtual domains and mailboxes, and extensive configuration for mail routing rules, while remaining known for a comparatively straightforward configuration file syntax relative to Sendmail.
Postfix is completely free and open source, with no licensing cost for downloading, installing, modifying or running it in any environment, personal or commercial.
The only costs associated with running Postfix are infrastructure costs (servers, IP addresses, and any managed hosting a team chooses) and the administrative time required to configure and maintain the mail server, since Postfix itself does not offer paid tiers or commercial support contracts from a single vendor.
Yes, Postfix is free and open-source software with no licensing fee.
Postfix was written by Wietse Venema at the IBM Thomas J. Watson Research Center, first released publicly in December 1998.
Postfix is a mail transfer agent that routes and delivers email over SMTP between mail servers; it is commonly used as the core mail-routing component of a Linux mail server.
No. Postfix is a lower-level mail transfer agent with no UI or API. Postal is a full open-source mail delivery platform built with a UI and API on top of MTA-level routing, and Postmark is an unrelated commercial hosted email API.
Postfix is released under the IBM Public License, and newer versions are also available under the Eclipse Public License 2.0.
The main alternative mail transfer agents are Sendmail, Exim and OpenSMTPD.
Not natively, but Postfix provides integration hooks to work with spam and virus filtering tools such as SpamAssassin.