I had a great time working in the Technical Learning Center (TLC) at the recent TechEd North America 2009 event in Los Angeles. It's always fun to talk to attendees and find out what they want to know about Exchange Server. Microsoft unveiled a lot of details about Exchange Server 2010 at the show, so it's natural that the TLC staff got more questions than usual about the new version.

The most common question I heard was entirely predictable: "If I'm on Exchange 2003, should I move to Exchange 2007 now or wait for Exchange 2010?" I heard this question asked, in different forms, by dozens of attendees representing all sizes of organization from all geographies. Unfortunately, there's not one simple answer; there are probably as many variations of answer as there are differences in Exchange deployment.

For example, one fellow I spoke to said that he still had one Exchange 5.5 server in his environment, along with a dozen or so Exchange 2003 servers—and a few Windows NT 4.0 domains! He estimated that it would take about a year for him to have everything moved over to either a Windows Server 2008 or Windows Server 2003 native-mode forest, and to expunge the old Exchange 5.5 server and all its mailbox data. In his case, the answer is simple: wait and move directly to Exchange 2010. Based on his description of the environment, there's not much point in expending resources to deploy Exchange 2007 later this year when the underlying directory infrastructure is in such a mess.

However, a more common situation is that of the numerous organizations who are poised to move to Exchange 2007 from Exchange 2003. Perhaps they want to take advantage of the much reduced I/O load—and corresponding increase in scalability—of Exchange 2007. Or maybe there are particular features, such as unified messaging, that are driving their upgrade requirements. For these organizations, the answer isn't quite so clear-cut.

Let's start with the presumption that most companies won't want to spend time, effort, and money on a double upgrade—first to Exchange 2007, then later to Exchange 2010. Many people I spoke with told me flat out that they could afford to upgrade once, but not twice. For those folks, their question was really better expressed as, "Is Exchange 2010 worth waiting for?" When phrased that way, I think the answer is a strong yes. Why?

  • For companies that are seeking relief from Exchange 2003's I/O characteristics, Exchange 2010 offers further improvement—as much as 50 percent by some estimates—over Exchange 2007's already-impressive gains.
  • The Exchange high availability story gets both simpler and more flexible with the introduction of database availability groups, thus easing another pain point for Exchange 2003 shops that want to move away from shared-storage clustering.
  • Every feature area in Exchange 2010 offers significant functionality improvements over Exchange 2007—from unified messaging's new Voice Mail Preview feature to the dramatically better OWA experience, these changes offer major benefits to system administrators and end users.

For the lucky few that can afford the luxury of doing two upgrades, or the unlucky few who have such unstable environments that they need to upgrade right away, it might still make sense to move to Exchange 2007 now, especially given that doing so will accomplish most of the heavy lifting of an Exchange 2003–to–Exchange 2010 upgrade.

However, I don't expect to see many companies fall into either of these categories. Anecdotal evidence so far tells me the opposite—but I'm willing to be proven wrong. We've cooked up a poll below to gather more explicit data to show what Exchange 2003 shops are planning on doing. You can also drop me a line to let me know what your migration plans are.

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