A while ago I came across a mailbox that needed to be deleted… but the assosiated useraccount was in an old domain that was no longer in the air and the mailbox didn’t go to “disconnected mailbox”.
So when I tried to delete the mailbox through the GUI, I got an error telling me that the associated user account could not be found.
While using the GUI, deleting the mailbox drove me next to mad… it would not go!

My solution was to be found in PowerShell 🙂

First use a command to get the mailbox (and it’s statistics):
$Emailbox = Get-MailboxStatistics | Where{$_.DisplayName -eq “Steve Jobs”}

Second use a command to delete it:
Remove-Mailbox -Database ” MailDatabase1” -StoreMailboxIdentity $Emailbox.MailboxGuid

And he was gone… finally!