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Network World - Even as social networking continues to gain in popularity, email remains the undisputed workhorse of messaging, far eclipsing all other forms of electronic communication. Email administration can be a costly function, especially for small to midsized organizations, and many administrators are looking for alternatives to enterprise-sized (and priced) commercial products.
For this review we tested six free or open source email server products: Apache James, Citadel, hMailServer, SmarterMail, Zarafa and Axigen. Most have commercial options, but we specifically limited our testing to the free or community editions. Some, like Zarafa and Axigen, can also scale to handle large volumes of users, while SmarterMail and Citadel are more suitable for small to midsized organizations.
The six products we chose fall into three categories: Linux-only, cross-platform and Windows only. Our Linux-only contenders are Citadel, an open source product with roots back to the early 1980s and Zarafa, a European product with several features to support mobile mail.
Cross-platform products are attractive for the obvious reason that they can run on both Linux and Windows platforms. In this category, we tested open source and Java-based Apache James, part of the well-known Apache Foundation, and Axigen, a commercial mail server that offers a free version for up to 100 users and runs on both 32- and 64-bit Windows as well as most Linux systems.
In pictures: 6 free email servers for small businesses
On the Windows side, we tested hMailServer, which has been around since 2002 and is available under the open source GPL license, and SmarterMail, which offers a free full version of its server product limited to 10 users on one domain.
The hands-down winner was hMailServer. Small and unobtrusive, hMail server is one of those products that simply works as advertised the first time and every time, maybe without some of the latest bells and whistles like ActiveSync and mobile mail. But hMail's core mail server functions are rock solid, and this product gets high marks for all the benchmarks that matter: ease of installation, ease of configuration, small, flexible code base, reliability and fault tolerance, and last but not least, no limitation on number of domains or users.
Of the runners-up, we have to give the edge to Citadel. This compact, Linux-based mail server was not only easy to install compared to most of the Linux candidates, but it also is long on features, fully open source and available in one-size-fits-all. If you are a small to midsize Linux shop, this is an excellent choice. The current UI is somewhat dated, but this is due to be corrected in the next release, which we previewed.
All the other test candidates are competent mail servers as well. Apache James is very appealing with its cross-platform availability and our only complaint is that version 3 with all its additional features is not yet available in a stable release. Zarafa provides good core mail server functionality in its community edition, but some functionality such as calendaring and extended Outlook support are available only in the commercial version. Another strong cross-platform candidate is Axigen, as it has one of the better user interfaces, both for administration and Web mail, but is limited in the number of users. SmarterMail provides a nice alternative to hMailServer on the Windows side and its biggest and maybe only drawback is the limitation on the number of users.