Free email servers for small businesses

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We tested six free or open source email server products: Apache James (cross-platform), Citadel (Linux-only), hMailServer (Windows-only), SmarterMail (Windows-only), Zarafa (Linux-only) and Axigen (cross-platform). Most have commercial options, but we specifically limited our testing to the free or community editions.

hMailServer

Pros: Unlimited use, easy to install and configure, flexible code base runs on most Windows versions.

Cons: Lack of native mobile and web support.

Citadel

Pros: Fully open source, no limits on users, small footprint, easy to install.

Cons: Dated GUI, may not scale well for larger organisations.

SmarterMail

Pros: Nice user interface, good support for mobile mail, informative tutorials.

Cons: Free version limited to 10 users on a single domain.

Apache James

Pros: Java platform runs on both Linux and Windows, 'mailets' provide modular design and flexibility.

Cons: Current stable release dated August 2009; no GUI.

Axigen

Pros: Cross-platform, great user interface, easy to install, includes help features.

Cons: Free version limited to 100 users.

Zarafa

Pros: Comprehensive mobile support, pleasing user interface, LDAP integration.

Cons: Community edition somewhat lacking in features, installation has quite a few prerequisites.