Script Download: GetDisconnectMailbox(PowerShell).ziphttp://gallery.technet.microsoft.com/scriptcenter/Get-disconnect-mailbox-in-6ffc50a0
As usual, the Exchange cmdlet could not easily get the disconnected mailbox, we need to Check the "DisconnectDate" from Get-MailboxStatistics. And Get-MailboxStatistics need to run one mailbox by one mailbox. This script can list of all disconnected mailboxes on your mailbox server.
You can find more All-In-One Script Framework script samples at http://aka.ms/onescriptingallery