Alternatives to Postfix
A widely used open-source mail transfer agent for routing and delivering email. The listings below can replace it for an important use case. Each note says what changes if you switch.
The original
Postfix
A widely used open-source mail transfer agent for routing and delivering email.
Replacements
Listings that take over the same core job as Postfix.
Exim
An open-source mail transfer agent for Unix systems with flexible routing and mail checking.
Exim is a GPL-licensed MTA offering very flexible routing and extensive checks on incoming mail, acting as a drop-in Sendmail replacement with a more complex configuration.
OpenSMTPD
A free SMTP server from the OpenBSD project for sending and receiving email.
OpenSMTPD comes from the OpenBSD project under the permissive ISC license and is simpler to configure than many SMTP servers, with a portable version for Linux.
Mox
An all-in-one open-source mail server for low-maintenance self-hosted email.
Mox replaces Postfix with one program that also covers IMAP and webmail, with built-in DKIM, SPF, DMARC and automatic TLS, though it is less widely deployed.
Similar software
Related functionality, not a direct replacement.
Dovecot
An open-source IMAP and POP3 server that stores mailboxes and serves them to mail clients.
Cyrus IMAP
An open-source email, contacts and calendar server with IMAP, JMAP, CalDAV and CardDAV support.
Mailu
A full-featured self-hosted mail server delivered as a set of Docker images.
docker-mailserver
A complete mail server with SMTP, IMAP, antispam and antivirus, packaged as a single container.
Google Postmaster Tools
Google's web dashboard for checking a sending domain's reputation and mail deliverability to Gmail.
