Email server software for Linux

mail transfer agent

Sendmail is a general purpose internetwork email routing facility that supports many kinds of mail-transfer and delivery methods, including the Simple Mail Transfer Protocol (SMTP) used for email transport over the Internet.

free software IMAP and POP3 server

qmail is a mail transfer agent (MTA) that runs on Unix. It was written, starting December 1995, by Daniel J. Bernstein as a more secure alternative to the popular Sendmail program. Originally license-free software, qmail's source code was later dedicated to the public domain by the author.

Exim is a mail transfer agent (MTA) used on Unix-like operating systems. Exim is a free software distributed under the terms of the GNU General Public License, and it aims to be a general and flexible mailer with extensive facilities for checking incoming e-mail.

Zentyal (previously known as eBox Platform) is an open source email and groupware solution based on Ubuntu Linux. The latest release (Zentyal Server 8.0 Development) took place on February 26, 2024.

mail-server software suite

free software electronic mail server

open source mail server

OpenSMTPD (also known as OpenBSD SMTP Server) is a Unix daemon implementing the Simple Mail Transfer Protocol to deliver messages on a local machine or to relay them to other SMTP servers. It was publicly released on 17 March 2013 with version number 5.3, after being in development since late 2008.