I am using Exmerge 2k to import users mailboxes yet I don't see all the exchange mailboxes. User accounts are in Unity. Even in Exchange System Manager, I don't see all the Exchange mailboxes. I saw this with my first install which wasn't an issue - I wasn't importing exchange mailboxes. (The mailboxes were created the first time a user logged into their Unity voicemail account.)
Even in Users and Computers I don't see the Exchange mailbox information. I do see e-mail addresses for the Exchange account.
I am running Unity 3.1.5, Exchange 2k (local and only Exchange server in the domain) and joined an existing AD domain.