With Exchange 2010 SP2 released, it’s past time for you to start putting all those old Exchange 2003 servers out to pasture, and any Exchange 2000 servers still hanging on out of their misery. The process to remove Exchange 2003 (or any other version) is not as simple as formatting the drive, but too often that is exactly what people do, and only then realize that to remove Exchange requires a process not too different from retiring a domain controller. In this post we will look at the process to remove Exchange Server from Active Directory and properly retire an old server, including the last legacy Exchange server your environment.

If you are going to remove the last legacy Exchange server from your Exchange 2007 or 2010 environment, there is a little more you need to do. Make sure you do not need any of the features from Exchange 2003 that are deprecated in 2007, like Groupwise connectors. If you are ready to go, here’s how to do it:

1. Ensure your account has both the Exchange Organization Administrator role on Exchange 2007, and the Exchange Full Administrator role on Exchange 2003.
2. Confirm that Internet mail flow doesn’t route through your Exchange 2003 server.
3. Verify that you have created Exchange 2007 Send connectors to replace all outbound SMTP connectors that may exist on that Exchange 2003, and that the Exchange 2003 server is not the smart host for any Exchange 2007 Send connector or other SMTP relay.
4. Make sure no clients are still configured to use the Exchange 2003 server.
5. Disconnect all mailboxes – You can move any remaining mailboxes to another mailbox server, or use Active Directory Users and Computers to delete the mailboxes from users that no longer need them.
6. Ensure that any public folders are hosted on another server and remove the public folders from this server. It can take hours for this process to complete since the change must be replicated to all other servers. Plan accordingly.
7. Make sure that no Offline Address Book is being generated on the server.
8. Delete any routing group connectors that connect the Exchange 2003 server groups and the Exchange 2007 routing group.
9. If you have Exchange 2003 recipient policies that are only Mailbox Manager policies and do not define e-mail addresses (they do not have an E-mail Addresses (Policy) tab), perform the following steps to delete the policies:
   a. In Exchange System Manager, expand Recipients, and then select Recipient Policies.
   b. To verify that a policy is only a Mailbox Manager policy, right-click the policy, and then select Properties. The Properties page must not have an E-Mail Addresses (Policy) tab.
   c. To delete the policy, right-click the policy, and then select Delete. Click OK and then click Yes.
10. If you have Exchange 2003 policies that are both E-mail Addresses and Mailbox Manager policies (they have both the Mailbox Manager Settings (Policy) tab and the E-mail Addresses (Policy) tab), perform the following steps to remove the mailbox manager portion of the policy:
    a. In Exchange System Manager, expand Recipients, and then select Recipient Policies.
    b. Right-click the policy, and then select Change property pages.
    c. Clear the Mailbox Manager Settings check box, and then click OK.
    Note: Don’t delete any e-mail address recipient policies that have e-mail addresses that you still want defined in your organization. Exchange 2007 will use those policies when provisioning new recipients.
11. On your Exchange 2003 or Exchange 2000 server, perform the following steps to move the public folder hierarchy from the Exchange 2003 or Exchange 2000 administrative group to the Exchange 2007 administrative group:
    1. In Exchange System Manager, expand Administrative Groups, right-click Exchange Administrative Group, select New, and then select Public Folders Container.
    2. Expand the Exchange 2003 or Exchange 2000 administrative group that contains the public folder tree, expand Folders, and then drag Public Folders to Folders under the Exchange 2007 administrative group.
12. Perform the following steps to delete the domain Recipient Update Services:
    1. In Exchange 2003 or Exchange 2000 System Manager, expand Recipients, and then select Recipient Update Services.
    2. Right-click each domain Recipient Update Service, and then select Delete.
    3. Click Yes.
13. You will not be able to delete the Recipient Update Service (Enterprise Configuration) by using Exchange 2003 or Exchange 2000 System Manager. Perform the following steps to delete the Recipient Update Service (Enterprise Configuration)by using ADSI Edit (AdsiEdit.msc):
    1. Open ADSI Edit, expand Configuration, expand CN=Configuration,CN=<domain>, expand CN=Services, expand CN=Microsoft Exchange, expand CN=<Exchange organization name>, expand CN=Address Lists Container, and then select CN=Recipient Update Services.
    2. In the result pane, right-click Recipient Update Service (Enterprise Configuration), click Delete, and then click Yes to confirm the deletion.
14. Remove Exchange 2003 Server components.
    You can either re-run the Exchange Server setup program, or use Control Panel, Add/Remove Programs to remove Exchange. Choose remove for each installed component.
15. Remove Exchange Server from Active Directory
    Launch the Exchange Management Console or Exchange System Manager from a remaining Exchange server.
    Expand Administrative Groups, Your Administrative Group Name, Servers.
    Right-click the retired server, click All Tasks, and then click Delete.
16. Microsoft recommends that you do not remove the original Administrative groups from an organization. Typically, when an administrative group is removed and mail begins to back up in the System Attendant mailbox, this indicates that the Free/Busy folder from the old administrative group was not replicated correctly to one of the remaining administrative groups. To resolve this issue, use one of the following methods:
    Method 1: Add a replica of the Free/Busy folder for the old administrative group to one of the remaining administrative groups. To do this, follow these steps:

In the Exchange Management Shell, run the following command:
get-publicfolder -Identity “\NON_IPM_SUBTREE\SCHEDULE+ FREE BUSY” -Recurse | fl name,Replicas
Note that at least one of the SCHEDULE+ FREE BUSY folders is missing an Exchange 2010 or Exchange 2007 server that is listed as a replica. The output may appear similar to the following:
Name : EX:/o=contoso/ou=Exchange Administrative Group (FYDIBOHF23SPDLT) Replicas : {}

In the Exchange Management Shell, run the following command:
set-publicfolder -Identity “\NON_IPM_SUBTREE\SCHEDULE+ FREE BUSY\<Name of Folder>” -replicas “<Target PF Database>”
For example, type:
Set-publicfolder –identity “\NON_IPM_SUBTREE\SCHEDULE+ FREE BUSY\EX:/o=contoso/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)” –Replicas “Server\Storage Group\Public Folder Database”

Verify that the public folder group now has a replica by using the command from step 1. In the following example, the folder now has a replica object:
Name : EX:/o=contoso/ou=Exchange Administrative Group (FYDIBOHF23SPDLT) Replicas : {Public Folder Database}

All users whose Free/Busy data is not populated must accept or decline a meeting request to populate the Free/Busy data.

17. After the last Exchange 2003 or Exchange 2000 server has been removed from the Exchange 2007 organization, the Write DACL inherit (group) right for the Exchange Servers group should be removed from the root of the domain by running the following command:

Remove-ADPermission “dc=<Domain>” -user “<RootDomain>\Exchange Enterprise Servers” -AccessRights WriteDACL -InheritedObjectType Group

18. After the last Exchange 2003 or Exchange 2000 server has been removed from the Exchange 2007 organization, you can also remove the legacy Exchange Domain Servers and Exchange Enterprise Servers security groups. Make sure they are empty, and not being used for any other purpose before you delete them.

 Many of these steps were taken from the Microsoft TechNet article: http://technet.microsoft.com/en-us/library/bb288905(EXCHG.80).aspx.

Keep an eye on both your Active Directory replication, and your mail queues for the next few hours to ensure that the deletion replicates fully, and that you didn’t miss anything that will cause mail to back up. With a little patience and by following these steps, you can remove Exchange 2003 safely.