Exchange 2010 message stuck in queue “A non-expirable message”

Be sure to perform this after hours as it will stop mailflow.

1. Stop the exchange transport service
2. Locate C:\Program Files\Microsoft\Exchange Server\Transport Roles\data\Queue and rename Queue to Queue_old
3. Restart the transport service

The Queue folder should automatically be recreated with no issues.

Sources

• http://social.technet.microsoft.com/Forums/exchange/en-US/fea6325f-eca1-492d-807c-880e3115cf9e/unable-to-delete-messages-from-queue?forum=exchangesvrgenerallegacy