Can open source replace Microsoft Exchange?

So, for now, any would-be Exchange replacement has to rely on reverse-engineering and an imperfect understanding of Exchange's protocols. Another problem, Jennings points out, is that Exchange is a moving target. "Exchange keeps getting better," Jennings points out.

That said, Exchange is also growing ever more costly and not everyone wants Exchange 2007's unified communications, which now includes everything from e-mail to voice-mail. Cost is often cited as the number one driver for companies that switch from Exchange to an open-source alternative.

However, that hasn't proven sufficient to move many customers from Exchange. Jennings said, "Various people have been pushing this idea for years, including yours truly, but it hasn't ended up with a lot of traction. Open-source e-mail servers have remained a niche thing."

Why is that? One reason is that none of the open-source programs are really ready to serve as drop-in Exchange replacements. There's also some additional work that needs to be done, and it's not work that Windows administrators are used to doing. Even a veteran Linux administrator, though, might find setting up a full-powered Exchange replacement for a good-sized company a challenge.

For example, Scalix 11.4 requires Apache, PostgreSQL, Tomcat, and either Sendmail or Postfix to be installed before it can work. That's not hard, but when you factor in the need for managing disk performance it becomes more of a problem. E-mail server applications, have trouble scaling, because of disk performance bottlenecks. To run a groupware server for more than a small business really requires shared disk arrays. Put it all together and you have a serious Linux system administrator's job, and it's not one that a former Exchange administrator is likely to be able to handle. So, while in the long run, the total cost of ownership is likely to favor a Linux/open-source solution, in the short run, getting an IT department to switch over from an Exchange-centric e-mail system isn't easy.

The answer? Well certainly advances in OpenChange and adoption of its work by other projects will help smooth out any remaining Outlook compatibility problems. Perhaps, an even more vital change to help open-source Exchange replacements' adoption though will be to make installing and maintaining them easier than it is today.

Are the open-source Exchange replacement programs good enough? Yes, I have no question that they are, but it's not just being good enough, or even cheap enough. It's about making it easy to give Outlook users a 99.9999 percent Exchange-like experience while making it easy for experienced Exchange administrators to deliver that experience to them. Only when these can be delivered will programs like Open-Xchange, Scalix, and Zimbra become important to business IT.

In the meantime, both Jennings and Radicati believe that Google's Gmail and the hosted Zimbra Collaboration Suite are more likely to replace Exchange. That's because they're not actually replacing Exchange, instead they're replacing Outlook with a Web-based e-mail interface. It may not be open-source, but software as a service (Saas) that actually ends up replacing Outlook/Exchange.

Of course, Microsoft is aware of this and they have their own SaaS Exchange plans. With that being the case, open-source groupware servers may yet have their chance to make the kind of impact in business e-mail that open-source programs already have in operating systems, Web servers and databases. Trite as it may be, this really is a case where only time will tell.