One or more users currently use this mailbox store. These users must be moved to a different mailbox store or be mail disabled before deleting this store.
ID no: c1034a7f
Exchange System Manager
This is despite the fact that you think you have already removed all the mailboxes off of this server. You follow the instructions in Microsoft Knowledgebase article 279202 but this makes no difference.
1. Run Active Directory Users & Computers.
2. Right-click your domain at the top of the tree and click Find.
3. Click the Advanced tab and then choose User from the Field button.
4. From the list of attributes displayed, choose Exchange Home Server.
5. Set the Condition field to Ends With and then type the name of your Exchange server into the Value field. Click Add to add this value.
6. Click the Find Now button which should now display the problematic objects.
The Exchange attributes can now be removed from these objects and the uninstall process attempted again.
Article ID: 555147 - Last Review: 14 Feb 2017 - Revision: 1