We get the following NDR:
Delivery has failed to these recipients or distribution lists:
Microsoft Exchange has been trying to deliver this message without success and has stopped trying. Please try sending this message again, or provide the following diagnostic text to your system administrator.
#550 4.4.7 QUEUE.Expired; message expired ##
Please help! Which diagnostics can i use in Exchange 2007 to see where this message is stopping and what the hold up is.