I recently had a couple of cases where E-Mails were not being processed from the queues anymore causing mailflow issues and new e-mails were building up in the submission queue.
As a result of those cases I have created a guide for troubleshooting such issues and have documented the main steps:
HOWTO increase the Logging Levels in Exchange 2003,2007 and 2010
*by default we have the following transport agents running on the exchange Transport Server in Exchange 2007 and Exchange 2010
Should this not help, we can also deactivate the antivirus software running on the HUB Servers.
For this we should implement the following procedure:
Go to the queue in the Exchange Management Console and right click the queue and select suspend
Messages will now be delivered.
Hope the information provided was helpful for you and clarifies the process of mailflow troubleshooting.
If you have any questions, please send me an Email to firstname.lastname@example.org
Great documentation!!! It was really helpful to me today!!!
I ran into this issue at the end of last year and have to go thru exactly these steps listed in this documents. Thank you for posting this document!