I always forget about this one.   I rarely use ExMerge as it is, but occasionally it’s a easy way to grab a copy of a mailbox off of the Exchange server.   In this case I needed to grab 5 mailboxes before I removed the users from the system.

But if you try and use the Administrator account to get an ExMerge copy, you will get errors.   Here’s the workaround:

http://support.microsoft.com/kb/823143