When trying to uninstall Exchange 2003 the following error can appear:
One or more users currently use a mailbox store on this server
This can occur even if there are no mailboxes on the server, or even if the mailbox store itself is no longer present.
In checking whether or not any mailboxes exist an AD lookup is performed. If there is a user acc that has the Exchange Home Server ADSI attribute (msExchHomeServerName) set to the Exchange server you wish to uninstall the error above appears. The user acc may not even offically have any Exchange attributes.
From a machine that has Exchange AD installed:
- Right click the Domain, choose find. On the Exchange tab ensure that 'Show only Exchange recipients IS NOT TICKED.
- Click Find.
- View > Choose Columns, select 'Exchange Home Server'. This lists data in the msExchHomeServerName attribute.
- Click the Exchange home Server column to sort and find the acc(s).
- If you do not need the user(s) delete them. If you do, navigate to the user using [http://technet.microsoft.com/en-us/library/bb124152(EXCHG.65).aspx ADSI Edit] or http://technet.microsoft.com/en-us/sysinternals/bb963907.aspx and clear the msExchHomeServerName AD attribute.
[http://technet.microsoft.com/en-us/library/bb124152(EXCHG.65).aspx Using ADSI Edit to Edit Active Directory Attributes]