SolutionBase: Migrating from Exchange Server 5.5 to Exchange Server 2007

Your company may have decided to sit out Exchange 2000 and Exchange 2003 updates, but now you've decided to make the jump to Exchange Server 2007. What's in store? In this article, Brien Posey shows what you'll face.
This article is also available as a TechRepublic download.

With Microsoft's discontinued support for Exchange Server 5.5, you might be tempted to upgrade your Exchange Server organization to Exchange Server 2007. Sadly, the upgrade process is much more involved than simply inserting an installation CD and running Setup. In this article, I will explain what is involved in making the transition to Exchange 2007.


Unfortunately, the process of migrating from Exchange 5.5 to Exchange 2007 is very elaborate and requires some serious planning. Exchange 5.5 is not compatible with Exchange 2007, so you will have to migrate all of your Exchange Servers to Exchange Server 2003 before you can even consider making the move to Exchange 2007. Exchange 2007 cannot be installed in an organization where there is even one Exchange 5.5 server.

After upgrading to Exchange 2003, you still have a lot of work ahead. Exchange 2007 does not support in-place upgrades, so you can't just put an Exchange 2007 installation CD into an Exchange 2003 server. Instead, you will have to buy at least one new server and install Exchange 2007 on to it. Only then can you begin migrating your mailboxes and public folders to Exchange 2007.

One more thing: don't underestimate the importance of training. Exchange 2003 is extremely different from Exchange 5.5: it uses a completely different management interface and relies on Active Directory. Despite Exchange 2003 being a temporary solution, you will still need to know how to deploy and maintain an Active Directory environment, and be familiar with the Exchange System manager and the Exchange 2003 database structure.

Just as Exchange 2003 is very different from Exchange 5.5, Exchange 2007 is very different from Exchange 2003. The management console has radically changed, as has the basic structure of an Exchange organization. For example, the routing and administrative groups that the Exchange 2003 organizational structure was based on do not even exist in Exchange 2007.

The migration process is very involved. I cannot possibly tell you everything you need to know within the confines of this article, so it is extremely important that you get training in Exchange 2003 and 2007, and Windows Server 2003; unless you have an expert at your disposal.

Since the migration process is so complicated, this article will focus on making the transition from Exchange 5.5 to Exchange 2003. Keep in mind that we are upgrading from Exchange 5.5 to Exchange 2003 with the goal of immediately upgrading to Exchange 2007. There are things in the Exchange 2003 upgrade process that might be better to do differently if you planned to use Exchange 2003 indefinitely.

What you will need

Your biggest purchase in preparation for an upgrade will be server hardware. At an absolute minimum, you'll need to buy one new server. Exchange 2007 requires 64-bit operating systems. Since all previous versions of Exchange Server required 32-bit operating systems, an in-place upgrade from Exchange 2003 to Exchange 2007 is impossible. Therefore, you will have to install Exchange 2007 on to a new server and migrate your Exchange 2003 mailboxes and public folders to it.

Ideally, you should purchase a second server. Just as it is impossible to perform an in-place upgrade from Exchange 2003 to Exchange 2007, it is also impossible to perform an in-place upgrade from Exchange 5.5 to Exchange 2003.

If your budget is tight and another server is out of the question, you do have a couple of other options. One option is to buy a high-end PC with lots of disk space, rather than a true server. You normally wouldn't want to use a machine like this as an Exchange Server (except in very small companies), but you are only going to be using this server until you can get your Exchange 2007 server into place.

Another option is to perform a rolling migration. You will only be able to do this if your Exchange 5.5 servers contain 64-bit processors and adequate hardware for running Exchange 2007. The idea behind this technique is that you would install Exchange 2003 onto your new server. You would then migrate all of the mailboxes and public folders from your Exchange 5.5 servers to the Exchange 2003 server. Once the migration is complete, you would decommission all of your Exchange 5.5 servers. Remember, Exchange 2007 cannot coexist with Exchange 5.5, so you will have to remove all of the Exchange 5.5 servers from the Exchange organization.

After the Exchange 5.5 Servers have been decommissioned, you can reformat one of the servers and install a 64-bit version of Windows Server 2003 and Exchange 2007. At that point, you can begin migrating your mailboxes and public folders to the Exchange 2007 server.

Another option is to perform a multi-step upgrade. The exact procedure varies depending on what operating system your Exchange 5.5 server is running. Suppose, for the sake of example, your Exchange 5.5 server is running Windows NT 4.0, the current operating system when Exchange 5.5 was released. As I said before, you can't perform an in-place upgrade to Exchange Server 2003; even if you could, Exchange Server 2003 will not run on Windows NT. You can however, perform an in-place upgrade from Exchange 5.5 to Exchange 2000. Again, though, Exchange 2000 can not run on Windows NT Server. The only version of Windows that Exchange 2000 is compatible with is Windows 2000. Therefore, you would have to follow these basic steps:

  • Upgrade the operating system to Windows 2000 Server
  • Upgrade Exchange 5.5 to Exchange 2000 Server
  • Upgrade Exchange 2000 Server to Exchange Server 2003
  • Upgrade Windows 2000 Server to Windows Server 2003

Although this technique will work, I don’t recommend using it unless you have to. This technique is very time-consuming, and there is a lot of room for error. Even if nothing goes wrong, it has been my experience that a server containing an OS upgraded from a previous version tends to be a little less reliable than a server containing a cleanly installed OS. Besides, this technique will only work if your Exchange 5.5 servers have hardware sturdy enough to support running Windows Server 2003 and Exchange 2003.

Your domain controllers

In the section above, I focused on upgrading Exchange Server and the underlying OS. You can't ignore the other network requirements though. More specifically, Exchange 2000, 2003, and 2007 are all dependent on Active Directory. Hopefully, you have already deployed an Active Directory environment. If not, you might search TechRepublic for articles that focus on Active Directory deployment planning. I cannot explain the full process within the constraints of this article, but I will give you a few pointers.

An Active Directory environment uses domain controllers, just like Windows NT. Regardless of how your network is configured right now, it is very important that you arrange your domain controllers so Exchange Server will not be running on a domain controller.

Exchange 2003 can run on a domain controller, but doing so is a big security risk. If someone were to compromise your Exchange organization, they could also compromise your Active Directory if Exchange was running on a domain controller. Furthermore, reboots take a really long time to complete when Exchange 2003 is running on a domain controller.

As if those reasons are not convincing enough, Exchange 2007 also does not support running on a domain controller. It will be easier to plan your domain controller placement now than to try to rearrange things in the middle of the upgrade.

DNS services

Active Directory cannot function without a DNS server. When you deploy the first domain controller in a Windows 2000 or Windows Server 2003 domain, you will be given the choice of either installing the DNS services directly onto the domain controller or using an existing DNS server.

My advice is to make sure your hardware is sufficient and install the DNS services directly onto the domain controller. All of the computers on your network are probably configured to use an ISP's DNS server for Internet domain name resolution. You will need to configure each of these machines to point to your internal DNS server instead. Keep in mind; if all you do is point your computers at an internal DNS server, then nobody will be able to resolve Internet-based domain names. To solve this problem, enter the IP address of your ISP’s DNS server as a forwarder on your own DNS server. Then, clients on your network will always look to the internal DNS server for name resolution. If name resolution fails, then your internal DNS server will pass the name resolution query to your ISP’s DNS server. When the query is answered, then your internal DNS server will pass the query result to the machine that requested it.

The eight-step plan

So far, I have given you a lot of background information and various options for completing an upgrade to Exchange 2003 targeted at an eventual upgrade to Exchange 2007. The actual steps you would use to complete the process depend heavily on the current state of your network. For example, if are there any Active Directory based domain controllers, then the procedure would be different than it would be if all of your domain controllers were running Windows NT. Since I can’t give you a step-by-step solution that will fit every deployment, the following is a list of eight general steps for an upgrade to Exchange 2003. (Just realize that this procedure might not be an exact fit for your individual needs.)

  1. Upgrade your domain to Active Directory. You don’t necessarily have to upgrade all of your domain controllers (although doing so is preferable), but you do need at least one domain controller that is running Windows 2003.
  2. Run a DS / IS consistency check on your Exchange 5.5 organization. This will ensure that all of the objects in the Exchange 5.5 directory are ready to synchronize with Active Directory. Keep in mind that you must verify that all of the sites and servers within the Exchange 5.5 organization can communicate with each other. Otherwise, running a DS / IS consistency check will wreak havoc on your Exchange organization.
  3. Configure an Active Directory connector between the Exchange 5.5 organization and Active Directory. This will cause Active Directory to synchronize itself with the Exchange Directory. You can accomplish this task by using the Exchange Server Deployment Tools included on the Exchange 2003 installation CD.
  4. Install Exchange 2003 onto your new servers. When you install the first instance of Exchange 2003, you will have to run ForestPrep and DomainPrep (included in the installation wizard) to prepare Active Directory schema for the installation. When the installation process completes, be sure to install the latest service packs and hot fixes for both Windows and Exchange.
  5. Verify that any user who has an Exchange 5.5 mailbox has a user account in Active Directory. Assuming your domain controllers are running Windows Server 2003, this should not be an issue, but it is important to check. Once you have confirmed the existence of these accounts, you can begin moving mailboxes and public folders to the Exchange 2003 server.
  6. If you are using connectors to foreign mail systems such as GroupWise or CC Mail, you will have to create alternate connectors on your Exchange 2003 server. After doing so, remove the external mail connectors from your Exchange 5.5 servers and verify that mail flow between the mail systems is still functional.
  7. Verify that all of the resources contained on your Exchange 5.5 servers have been moved to your Exchange 2003 servers. This is also a good time to verify that everything is working correctly on the new servers. After doing so, you can begin decommissioning your Exchange 5.5 servers by uninstalling Exchange.
  8. After all the Exchange 5.5 servers have been removed from the Exchange organization, switch the organization to Native Mode. Once the organization has been placed into native mode, there is no going back to mixed mode; you will never be able to join another Exchange 5.5 server to the organization again.

Exchange 2003 first, then 2007

As you can see, the first step in moving to Exchange 2007 is to transition your organization into running Exchange 2003. You can read about the rest of the migration process in my article on upgrading from Exchange 2003 to Exchange 2007.


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