I migrated all of our user's mailboxes last night. This morning, no one's e-mail was showing new messages and Outlook would not connect to Exchange. I picked one user and did some experimentation based on forum articles (e.g. added his user to the SBS Console was the main thing). All of a sudden after a transport restart, everyone started working except this one user. The queue shows "the mailbox recipient does not have a mailbox database". I have disconnected and reconnected his mailbox to no avail.