Ok without drawing it out too much. Running Exchange 2010, did a dcpromo on another box that messed stuff up so I repromoted it. All is well except for one user. He is no longer in AD. I could just recreate him, but his mailbox appears to have vanished as well.
It is not listed under disconnected mailboxes in the MMC. Here is the odd thing, if I run Get-MailboxDatabase "Mailbox2" | Get-MailboxStatistics his mailbox is there with 29K+ items. However if I run Get-Mailbox and dump it to text his mailbox doesn't list.
It is like Exchange has it, but I need to reconnected it to an AD user. I've already recreated his AD user. My PS is admittedly weak, but I'm sure there is a cmdlet to recreate the link, since the mailbox is clearly there.