Having Trouble Uninstalling Exchange... Mailbox exists

Taken from: http://hellomate.typepad.com/exchange/2004/02/having_trouble_.html

So where are these users? You've moved all of them off this server. The person I was talking with followed the remaining instructions in 279202, which go on to show you how to use LDP to view the remaining mailboxes on the server. The problem was that the result of the LDP output showed that there were only 2 system mailboxes left on the server, which can be ignored.
A good way to try to find these missing users is to use good old Active Directory Users and Computers. Here's what to do:
1. Run ADUC.2. Right-click your domain at the top, and choose 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 your Exchange server name into the Value field. Click Add to add this value.6. Now click the Find button, and hopefully you'll see the troublesome user listed in the results window. You should then be able to remove the Exchange attributes from these user accounts and proceed with the uninstall.

So where are these users? You've moved all of them off this server. The person I was talking with followed the remaining instructions in 279202, which go on to show you how to use LDP to view the remaining mailboxes on the server. The problem was that the result of the LDP output showed that there were only 2 system mailboxes left on the server, which can be ignored.
A good way to try to find these missing users is to use good old Active Directory Users and Computers. Here's what to do:
1. Run ADUC.2. Right-click your domain at the top, and choose 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 your Exchange server name into the Value field. Click Add to add this value.6. Now click the Find button, and hopefully you'll see the troublesome user listed in the results window. You should then be able to remove the Exchange attributes from these user accounts and proceed with the uninstall.