I recently had to restore a system to a backup I had that was a month old. I had a file-level copy of the Exchange database files that was current. I copied the Exchange database files into their proper locations and mounted them in Exchange. Exchange is working, but an interesting side effect is that two mailboxes are missing. Both of these mailboxes were associated with AD accounts that were created AFTER the system restore point. I would think the mailboxes would still be present in Exchange, at least under disconnected mailboxes.
Is this expected? The other mailboxes appear up to date. I was able to recreate the additional two mailboxes manually and restore the data using PST imports. Still, I found their absence strange.