One of our users failed to receive 2 emails from an @msn.com business email address which vcard attachments. The sender @msn was receiving NDR's from our Exchange 2003 server. I did a message trace and saw that the NDR was sent however no clue as to why it was not delivered or not that I could interpret. We use Reflexion Spam filtering which allowed the message.
Our IMF threshold on the server was at 8 but it was set to no action.
We are getting informational entries in the event viewer:
9096 Mad Monitoring thread initialized
9661 Default filter level set to 8
NDR received @MSN:
Arrival-Date: Thu, 3 Apr 2014 15:48:42 -0600
X-Display-Name: user name
I tried searching for more information but could not find any indication why the server rejected the message. When I asked the sender @MSN to send me the vcard to a different domain it came through however the body of the email had this text (with +AEA- instead of @ and some other similar replacements.) Any help isolating the cause would be appreciated. So far we only know of this one instance of this issue. All other mail flow is problem free. I checked the SPF for the sender. Everything seems fine.
From: MSN User, Company name +AFs-mailto:msnuser+AF8-597+AEA-msn.com+AF0-
Sent: Thursday, April 03, 2014 5:01 PM
Subject: FW: Delivery Status Notification (Failure)
From: postmaster+AEA-ourdomain.com +AFs-mailto:postmaster+AEA-ourdomain.com+AF0-
Sent: Thursday, April 03, 2014 3:51 PM
Subject: Delivery Status Notification (Failure)
This is an automatically generated Delivery Status Notification.
Delivery to the following recipients failed.