Can open source replace Microsoft Exchange?

Open source projects and vendors are trying a variety of technical approaches to replacing the expensive but ubiquitous Microsoft Exchange. While none is yet a drop-in replacement, some administrators can get a TCO advantage by switching.

Once upon a time at a NASA space flight center a long way away, I was an e-mail administrator. At the time, the 1980s, e-mail was still chaotic. The RFC 822 standard was only beginning to bring rhyme and reason to e-mail. One of RFC 822's competitors, the Common Messaging Calls (CMC) X.400 standard, wasn't making much progress, but then Microsoft adopted it in 1992, added the concepts of folders to it, and re-named the result Mail Application Programming Interface (MAPI). And, ever since, the e-mail world can broadly be divided into two camps: the RFC 822 Internet compliant e-mail group and the MAPI-compliant Microsoft Outlook/Exchange pack.

Many of us assume that all e-mail works by using such RFC-822isms as e-mail addresses that look like "" Not so. MAPI takes a quite different approach. In addition to simply handling e-mail, extended MAPI and Collaboration Data Objects (CDO), which became Microsoft's default protocol set in Exchange 2003, added the power to manage calendars and addresses. So it is that Exchange and Outlook, while primarily used for e-mail, is also a groupware package.

And, I might add, a very popular one. A recent survey by Ferris Research revealed that Exchange has about 65 percent market share across all organizations. Lotus Notes/Domino is a distant number two with 10 percent of the market. POP/IMAP, (Post Office Protocol/Internet Message Access Protocol), the usual way incoming RFC-822 mail is handled? All the dozens of RFC-822 mail servers, including Sendmail, Qmail, and Postfix combined, have only 15 percent of the business/organization e-mail market.

As for the open-source groupware servers that try to directly compete with Exchange, such as Scalix, Open-Xchange, and Zimbra, Richi Jennings, a Ferris Research analyst, dismissed them as being mere 'noise' in the business e-mail market.

If you look outside the US, it's a somewhat different story. Sarah Radicati, CEO of The Radicati Group, estimates that in EMEA (Europe, Middle-East and Africa) open-source e-mail servers, lead by Germany-based Tobit have about 10 percent of the business e-mail market. Still, Radicati also estimates that Exchange is the dominant e-mail/groupware server with 37 percent of the world e-mail business market.

In other server areas, open source has made great gains against Microsoft's and the Unix vendors' proprietary programs. You only need mention Apache, Linux and MySQL to see this. Why is it that in business e-mail that while open-source e-mail servers are very popular with Internet service providers, they've been unable to make any substantial gains against Exchange?

One of the reasons is that Microsoft Outlook has been, continues to be, and looks to remain the e-mail client of choice for businesses. While open-source end-user applications in other categories, such as Firefox for the Web browser and OpenOffice for the office suite, have made impressive inroads on Windows desktops, open-source e-mail and groupware clients are still niche products.

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Steven J. Vaughan-Nichols
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