7 Best Linux Mail Servers of 2021

For transmitting successfully, the mail server uses a Mail Transfer Agent (MTA) a protocol is known as SMTP (Simple Mail Transfer Protocol) to perform its task. Let’s have a look at 7 most popular mail servers that run under Linux which we can trust with our mails.

You can also check the our What is Linux article

Table of Contents

1. Exim

Exim was developed as a message transfer agent at the University of Cambridge for use on Unix systems connected to the Internet. It is possible to install Exim instead of Sendmail, despite its configuration is a little bit different. It gets frequent updates for bug fixing. It has excellent customization and configuration capabilities. On the security side, it comes with three log mechanisms named as the main log, panic log, reject log. In addition to these features, it supports MySQL, PostgreSQL, SQLite, Oracle DB, and Redis databases and even more.

Download Exim Mail Server

Link: https://www.exim.org/mirrors.html

2. Postfix

Postfix that was founded by a Google software engineer, Wietse Venema runs not only on Linux also AIX, BSD, HP-UX, IRIX, MacOS X, Solaris, Tru64 UNIX, and other UNIX systems. And it supports MySQL, Memcache, SQLite, PostgreSQL, LDAP, CDB, and Berkeley Database as data storage. Postfix can be defined as an effective open-source mail server with its features as junk mail control, database support, and convenient log managements.

It comes with a content filter, access control mechanism, virtual domain support, configurable status notifications. It can deliver over 300 emails per second from a single Postfix instance. By providing defense mechanisms against malware and spambots, it offers a secure service.

Download Postfix Mail Server

Link: http://www.postfix.org/download.html

3. SquirrelMail

SquirrelMail that is a standards-based webmail package written in PHP includes built-in pure PHP support for the IMAP and SMTP protocols. Moreover, it comes with all pages render in pure HTML 4.0 for maximum compatibility across browsers. SquirrelMail has some benefits like easy configuration and installation, strong MIME support, address books, and folder manipulation. As SquirrelMail is licensed under the GNU General Public License (GPL), it is free to use.

Download SquirrelMail Mail Server

Link: https://squirrelmail.org/download.php

4. Axigen

Axigen has innovative features including an integrated mailing list server, malware, and spam protection mechanisms. This mail server software runs on Linux, Windows, or Docker. It has local and remote access, can easily synchronize mobile. On the security side, it comes with extensive security toolset. It is available for many Linux distribution but you have to pay after use free trial full-featured for 60 days.

Download Axigen Mail Server

Link: https://www.axigen.com/mail-server/download/

5. Citadel

One-year-old mail server software Citadel is an open-source software developed for Linux and BSD Unix distributions but supports most systems. It comes with a packed of features include e-mail, calendar, address books, bulletin boards, mailing list server, instant messaging and more. It has its own implementation of standard server protocols like SMTP, IMAP, Sieve, POP3, XMPP. For the storage of all contents, Berkeley DB database is preferred. OpenLDAP and Microsoft Active Directory are supported by Citadel.

Download Citadel Mail Server

Link: https://www.citadel.org/download.html

6. Zimbra Email Server

Open-source software Zimbra Collaboration Suite (ZCS) is an efficient mail server for Linux users. It transfers messages efficiently and takes less time to migrate with its powerful migration tools. It also comes with additional features such as group calendars, and document sharing with flexible tooltips, drag-and-drop items, and convenient UI menus. It has also mobile web client application and is ready for using the private and public cloud as well as a closed-source enterprise edition. For strengthening security, Zimbra provides a real-time backup feature.

Download Zimbra Email Server

Link: https://www.zimbra.com/downloads/

7. Horde

Horde Groupware Webmail Edition enables users to read, send and organize email messages and manage and share calendars, contacts, tasks, notes, files, and bookmarks with the standards-compliant components from the Horde Project. Horde Groupware Webmail Edition has many features including IMAP and POP3 webmail client, 3-pane and 3-column-layouts, message filtering, HTML message composition with WYSIWIG editor, shared IMAP folders, and more.