Cleaning Up Exchange 2003 Remnants

When a company with an existing Exchange Server organization begins adding Exchange 2007 servers to the mix, it is tempting to remove the old Exchange 2003 servers immediately upon completion of the migration process. However, it has been my experience that immediately decommissioning legacy servers is a big mistake. In this article, I will explain why this is the case, and what you need to do to gracefully remove legacy mailbox servers after a migration.

Why Wait?

If you have recently deployed an Exchange 2007 mailbox server and migrated all of the mailboxes from an Exchange 2003 server to it, you’re probably ready to decommission the legacy server. Even so, I would advise waiting for at least two weeks before you pull the plug on Exchange 2003. The reason why I say this is that if your users are using Outlook then their Outlook profiles are currently going to be directed to the old Exchange 2003 mailbox server. As the users begin to log on for the first time after the migration, Outlook should realize that mailboxes have been moved, and redirect each user’s profile to the new mailbox location.

If you remove the old mailbox server before users have had a chance to log onto the new server, then there’s a good chance that Outlook will not be able to automatically redirect the users profile to the new mailbox location. Waiting at least two weeks to pull the plug on the old mailbox server ensures that even users who are currently on vacation have a chance to log on, and have their profiles redirected before you decommission the old server.

The Decommissioning Process

Contrary to what I have read on a couple of websites, decommissioning and old mailbox server (or any Exchange Server for that matter) involves more than just shutting the server down and unplugging it. That’s because the majority of Exchange Server’s configuration information is stored in the Active Directory. Even if an old server has been taken off-line, the references to the server remain in the Active Directory and the rest of the Exchange Server organization assumes that the legacy server is still a part of the organization. This can lead to some rather nasty side effects, such as messages backing up in queues to nowhere.

Properly decommissioning an old mailbox server involved three primary steps:

1. You must remove all routing group connectors from the server.
2. You must uninstall Exchange from the server.
3. You must remove the appropriate routing groups from the Exchange Server organization.

I want to spend the remainder of this article focusing on routing groups and routing group connectors. Before I do though, I just want to mention that step number two requires you to uninstall Exchange Server. Before you can do that, you must have removed all mailboxes and public folders from the server. For the purposes of this article, I am assuming that you have done this as a part of the migration process.

Routing Group Connectors

As you have probably heard, Exchange Server 2007 does not use routing groups, and therefore routing group connectors are not even necessary in organizations running solely on Exchange Server 2007. The first part of the decommissioning process involves removing the routing group connectors from the server that you’re decommissioning. I will walk through the process in a step-by-step manner in part two of this series. For now though, I wanted to mention that you have to be careful about which routing group connectors you remove.

The catch is that you cannot indiscriminately delete routing group connectors. If a routing group connector serves as the only link between two routing groups or if it served as the only link between Exchange Server 2003 and Exchange Server 2007, and you delete it, then communications between routing groups will cease to function.

In order to prevent this from happening, you need to construct a topology diagram of your Exchange Server organization, and figure out the specific purpose of each routing group connector. By doing so, you can figure out which routing group connectors can be safely removed, and which ones would have serious consequences if you remove them.

If you do determine that you cannot remove a routing group connector without causing problems, then you need to create a routing group connector on a separate server. This routing group connector should serve the same purpose as the one that you are about to delete. Once you have an alternate connector in place, you can safely remove the routing group connector from the legacy Exchange server.

Removing Routing Group Connectors

Before you can remove the last Exchange 2003 server from your Exchange organization, you have to remove the routing group connector that connects your Exchange 2003 routing group to the Exchange 2007 routing group. The easiest way to accomplish this task is to use the Exchange System Manager.

To do so, open the Exchange System Manager and navigate through the console tree to Administrative Groups | your administrative group | Routing Groups | First Routing Group | Connectors, as shown in Figure A. Now, simply right-click on the routing group connector and choose the Delete command from the shortcut menu. You will have to repeat this process for any other routing group connectors that may still exist.

You also have the option of using the Exchange Management Shell to get rid of any remaining routing group connectors. To do so, you would use the Remove-RoutingGroupConnector command. The syntax for this command is:

 ​Remove-RoutingGroupConnector –Identity <routing group connector> [-confirm [<switch parameter>]] [-DomainController <domain 

controller’s fully qualified domain name]

It can be a little bit tricky to use this command, but when you do the actual command that you type will usually look something like this:

​Remove-RoutingGroupConnector -Identity "Exchange Administrative Group (FYDIBOHF23SPDLT)Exchange Routing Group (DWBGZMFD01QNBJR)Ex2007 to Ex2003 RGC" 

-DomainController dc1.contoso.com

You can see a much more detailed explanation of how to use this command here.

Redirecting the Recipient Update Service

Another task that you will have to complete as a part of decommissioning your final Exchange 2003 server is to redirect the Recipient Update Service. Exchange Server 2007 does not even use the Recipient Update Service, but you must redirected it before you will be able to uninstall Exchange Server 2003.

The process of redirecting the Recipient Update Service is fairly simple. Begin the process by opening the Exchange System Manager, and then navigate through the console tree to Recipient | Recipient Update Service. When you do, the details pane should display two separate listings for the Recipient Update Service. One of these listings refers to the Enterprise Configuration, and the other refers to the individual domain.

At this point, you should right-click on the Recipient Update Service (Enterprise Configuration) object, and choose the Properties command from the shortcut menu. When you do, Windows will display the Recipient Update Service (Enterprise Configuration) Properties sheet.

As you can see in Figure C, this property sheet contains a listing for a specific Exchange server. Click the Browse button next to the Exchange server, and you will be given the opportunity to enter the name of another Exchange server. Enter the name of an Exchange 2007 server, and click the Check Names button to verify the existence of the server that you have specified. Assuming that the name is resolved correctly, click OK.

Figure C Click the Browse button located next to the Exchange Server.

Click OK again to close the Recipient Update Service (Enterprise Configuration) Properties sheet. You must now repeat the procedure, but this time on the domain level instance of the Recipient Update Service. When you’re done, right-click on the Recipient Update Service (Enterprise Configuration) object, and choose the Update Now command from the shortcut menu. I also recommend updating the domain level instance of the Recipient Update Service in this same way.

Conclusion

You should now be able to successfully uninstall Exchange Server 2003. When the process completes, I strongly recommend verifying that external SMTP mail is still flowing. If not, then you may not have updated your DNS MX record to point to the appropriate Exchange 2007 server.