Scenario: A mailbox is disabled from an AD user account but it’s still present in Exchange as a disconnected Mailbox. To view the disconnected mailbox: Get-MailboxStatistics | Where DisconnectDate -ne $null
Resolution: Run the following commands:
Connect-Mailbox “Display Name” -Database “DB Name” -user “AD User Object Name”
Example:
Connect-Mailbox “John Jacob” -Database DB03 -user “jjacob”
Ex-Shell 