Exchange 2003 SP2: Migrate or Wait?

Second, you need to create a plan for hardware upgrades. Exchange 5.5 hardware requirements are modest by current standards, but many sites that are still using Exchange 5.5 have needed to upgrade their hardware since the release of Exchange 5.5 (especially given that hardware vendors have continued to drive down the price of high-availability features such as hot-swappable disks and redundant power supplies). If you're still running Exchange 5.5 on your original servers, you'll probably need to replace them; this would be a great time to ensure that the servers you buy are 64-bit capable so you can easily move to Exchange 12 when it ships.

Third, you have to upgrade Exchange software on the servers. Microsoft doesn't support in-place upgrades from Exchange 5.5 to Exchange 2003. You can upgrade your Exchange 5.5 servers to Exchange 2000 and then to Exchange 2003, or you can just install a new Exchange 2003 machine and move the Exchange 5.5 mailboxes to it. This latter approach is simpler, safer, and faster.

Fourth, and sometimes most troublesome, is that most messaging environments have lots of additional "stuff" that has to be upgraded and maintained. You'll need to replace any antivirus scanners, fax gateways, or other add-ons that run on your Exchange 5.5 servers. In some cases, you might find that some older products are unavailable in a version that works with Exchange 2003; in those cases, you'll need to either keep a 5.5 site around to keep running those products or find other similar products that do what you need.

This sounds like a lot of work, and it can be. However, in support of migration, by moving to Exchange 2003, you can cut the number of email servers required. If so, you might end up saving money on your upgrade. Individual circumstances will vary, but many companies see the number of deployed servers drop by 30 to 50 percent or more when Exchange 2003 is deployed. This is compelling evidence in support of migrating, given that reducing server count is perhaps the fastest way to reduce the cost of messaging operations (for any system, not just Exchange!).

Upgrading from Exchange 2000
Upgrading from Exchange 2000 to Exchange 2003 is much simpler than migrating from Exchange 5.5.You know that AD is already set up and working; not having to set up AD or learn how it operates tends to raise administrators' comfort levels. Also, Microsoft supports in-place upgrades from Exchange 2000 to Exchange 2003. Of course, just because Microsoft supports something doesn't mean that you should use it; there are arguments both for and against in-place upgrades. (See "A Religious Debate: Upgrade in Place vs. Reinstall," September 2005, InstantDoc ID 47614.) One compromise is to set up a new Exchange 2003 computer and use it to hold mailboxes as you upgrade. Suppose you have four Exchange 2000 servers: A, B, C, and D. You set up a new server, which I'll call E, and move mailboxes from A and B to E. You can then safely upgrade A and B to Exchange 2003, move the mailboxes back from E, and repeat the process with C and D.

Of course, a more likely outcome is that you move the mailboxes from A and B and leave them on E, decommissioning A or B (or both, and consolidating their workload onto a single server). The same site-and server-consolidation arguments that apply to Exchange 5.5 migrations also apply to Exchange 2000 upgrades. Exchange 2003 also offers scalability improvements beyond Exchange 2000. In the past, Microsoft has offered trade-up programs for organizations that buy the current version of a server product before the next version ships; they may or may not do this again for Exchange 12. Even if they don't, the increased security and capability of Exchange 2003 make it a worthwhile upgrade for shops using Exchange 2000 now.

Don't Wait for Exchange 12
By now, it should be pretty clear that the best solution for most organizations is to upgrade, or migrate, to Exchange 2003 now, rather than wait for Exchange 12. By doing so, you get many immediate benefits, including improved security, easier management, better stability, and a variety of features (including wireless and mobile access and support for Outlook 2003's Remote Procedure Call over HTTP—RPC over HTTP) that will make your messaging environment more stable, less expensive to operate, and more pleasant for both administrators and users.