Example Event Viewer Error
A non-expirable message with the Internal Message ID 92927 could not be categorized. This message may be a journal report or other system message. The message will remain in the queue until administrative action is taken to resolve the error. Other messages may also have encountered this error. To further diagnose the error, use the Queue Viewer or the Exchange Mail Flow Troubleshooter.
Event ID 9213
I had this issue recently with an Exchange 2010 SP1 server. I had a message stuck in queue that was intended for Journaling, however it had a content conversion error as the email came from a Blackberry device. I didnt want to have to rebuild the mail queue for 1 email so I simply removed the message using PowerShell doing the following:
Get-Message | fl
Remove-Message -Identity "SERVERNAME\Submission\41"