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From Exchange 5.5 to 2003 in a single bound

There is a way to upgrade from Exchange 5.5 to 2003 without buying a copy of Exchange 2k. It's more difficult than an Exchange 2000 upgrade, but it may be worth your while.

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I have talked to several people in the past few weeks who have told me that their organizations are going to move from Exchange 5.5 to Exchange 2000. When I asked them why they're implementing Exchange 2000 rather than Exchange 2003, the answer I got every time was, "you can't upgrade from Exchange 5.5 to Exchange 2003."

This is only partially true. There is a way that you can upgrade from Exchange 5.5 to Exchange 2003 without having to buy a copy of Exchange 2000. The method is a little more difficult than an Exchange 2000 upgrade, but I believe it is worthwhile. Exchange 2003 has more features than Exchange 2000 and also contains corrections to many of the bugs and security issues in Exchange 2000.

In this article, I explain what you need to do to upgrade from Exchange 5.5 directly to Exchange 2003.

Preparing Windows

In order to run Exchange 2003, at least one domain controller must be running Windows 2000 with Service Pack 3 or higher or Windows Server 2003. Any servers that will be running Exchange 2003 must have the same.

Preparing Exchange 5.5

Before you even think about an upgrade, you need to take some time and prepare your Exchange organization:

  1. Verify that all of your Exchange servers are running Service Pack 4 or higher for Exchange 5.5. Service Pack 4 isn't an absolute requirement, but it will make your life a lot easier.

  2. Make sure you do not have any servers running Exchange 5.0. If you do, upgrade them to Exchange 5.5 before continuing.

  3. Confirm that each existing Exchange mailbox is linked to an Active Directory user account.

  4. Also make sure that the designated owner of each mailbox exists within the Active Directory. This isn't an absolute requirement either, but even though this is a long and tedious task, it will make your life easier in the long run.

  5. Now you must perform a similar procedure with your Exchange public folders. Go through each folder and take a look at the names on the distribution list and the names in the access control list. Verify that each name listed corresponds to a valid Active Directory account.

Setting up a temporary server

I understand that companies have limited budgets and that you probably don't want the expense of adding additional Exchange servers to your organization. But you can't just install Exchange 2003 on top of Exchange 5.5.

The easiest way of accomplishing the upgrade is to set up an Exchange 2003 server, and then move your mailboxes and public folders to it. Before you decide that this approach is too expensive, let me explain how you can do this on a budget.

Rather than going out and spending $30,000 on a new server, buy a PC that has enough hard drive space to store your Exchange information store. You can set this PC up as a temporary server and then use it as a workstation later on. You don't have to worry about software licenses for this temporary server either. Microsoft allows you to download 90-day trial versions of Exchange Server and Windows Server.

The upgrade

The actual migration process is pretty simple:

  1. The first thing you will do when installing your temporary server is to install an Active Directory connector. This will update the Active Directory so that it can support your Exchange organization.

  2. After that, configure recipient and public folder connection agreements. This establishes translation rules for synchronizing Active Directory's mail-enabled objects with those objects that are still being stored in the Exchange 5.5 directory. You will see a warning message if your domain is running in mixed mode, but don't worry about it for now.

  3. Next, migrate the mailboxes, public folders and connectors to the temporary server.

  4. Decommission the now empty Exchange 5.5 server.

  5. Install Exchange 2003 onto the decommissioned server and move your mailboxes, public folders and connectors to the server.

  6. Once you have finished upgrading all of your Exchange servers, you can decommission the temporary server.

  7. Now switch your Exchange organization to native mode so that you get full Exchange 2003 functionality.

If you have any Windows NT backup domain controllers in your organization, you might also consider upgrading them to Windows 2000 or Windows 2003 so that you can set Windows to native mode as well. This not only gives you additional functionality, it also eliminates the need to support legacy LanMan replication.


  1. Download trial copies of Windows and Exchange and then set up a PC as an Exchange server.

  2. Connect the temporary server to your existing Exchange organization.

  3. Move all the mailboxes and public folders off one of your existing Exchange servers and onto the temporary server.

  4. Uninstall Exchange 5.5 from that server and install Exchange 2003.

  5. Move the mailboxes and public folders off of the temporary server and back onto your production server where they belong.

  6. Repeat the process for each remaining server.

  7. When all servers have been upgraded to Exchange 2003, remove the temporary server from the Exchange organization and promote the organization to Exchange native mode.


Even though an upgrade to Exchange 2000 is easier to perform, I honestly believe that migrating from Exchange 5.5 directly to Exchange 2003 is the better upgrade path.

About the author: Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server and IIS. Brien has served as CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. As a freelance technical writer he has written for Microsoft, CNET, ZDNet, TechTarget, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal Web site at

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