Receiving email with attachment error coming from a specific domain
Posted on 2011-10-28
We have a customer that can send mail to our internal exchange server just fine but when they send us an email with any attachment (small in size), they get the following NDR...
The server has tried to deliver this message, without success, and has stopped trying. Please try sending this message again. If the problem continues, contact your helpdesk....
#550 4.4.7 QUEUE.Expired; message expired ##
Any ideas why this particular sender would be getting this reply?