Simon or anyone else, have you ever seen a blank NDR from Exchange? There is a user trying to email a legimate email address on a Exchange server I manage, and all they get in exchange is an NDR message with no error code, it reads as follows:
Subject: Delivery Status Notification (Failure)
This is an automatically generated Delivery Status Notification.
Delivery to the following recipients failed.
Looking on the Exchange server Message Tracking Center, I have pulled up this log, and all it is saying is:
3/28/2007 5:46 AM SMTP: Message Submitted to Advanced Queuing
3/28/2007 5:46 AM SMTP: Started Message Submission to Advanced Queuing
3/28/2007 5:46 AM SMTP: Message Submitted to Categorizer
3/28/2007 5:46 AM SMTP: Message Categorized and Queued for Routing
3/28/2007 5:46 AM SMTP: Non-Delivered Report (NDR) Generated
I am not sure where to proceed from here. Usually I would take the NDR error reason and troubleshoot, but obviously I can't this time around.