Question:
When e-mail messages are not being delivered and the MTA queue is backed up and all the services is running, what could be another step I can take to troubleshoot the problem?
Answer:
The first step you should take whenever this happens is to double-click one of the messages in the queue and read the dialog box given for more information. Typically it will give you an error code expressing why the message is stopped there and you can use that to diagnose the problems further.