XCON: NDR is not Received When Sending to Bad PAB Entry

SYMPTOMS

When a Microsoft Exchange user sends a message to a recipient in their Personal Address Book (PAB), they not receive a Non-Delivery Report (NDR) if the PAB entry is invalid. This problem will only occur in the following circumstance:

1. The message has been addressed to an Exchange user in another Microsoft Exchange Site whose address is in the originator's PAB. The PAB entry has become invalid either because they have been deleted from the system or their original Site no longer exists in the Microsoft Exchange Organization.

   as 1984.

The message to the invalid PAB entry can be tracked by setting the X.400 Service category of the MSExchangeMTA to Maximum logging in the Microsoft Exchange Administrator program. By looking for the 271 and 272 events in the Windows NT Event Viewer Application log, you will see that the message gets sent to the destination Microsoft Exchange Message Transfer Agent (MTA) successfully, a 271 event, then the resulting NDR from this system is received OK, a 272 event, and finally the MTA then passes this on to the Microsoft Exchange Information Store (IS), another 271 event. However, the originator of the message does not receive the NDR.

If you turn on maximum logging for the Information Store (IS), specifically:

   MSExchangeISPriv/Transport Sending & Transport Delivering
   MSExchangeISPriv/Transport/General/<all categories>

   Event ID : 2026
   Source : MS Exchange Private
   Type : Information
   Category : Transport
   Description : The delivery of a report failed due to error 00000BB8.
   The report has been deleted.

CAUSE

The MTA was not correctly handling Distinguished Name (DN) addresses. The MTA now checks these before sending and will NDR the message back to the originator with the following diagnostic information:

   The recipient could not be transferred because it could not be
   downgraded.

WORKAROUND

The workaround for this is to use versions of the MTA greater than or equal to the following:

   Exchange 4.0 : 996.56
   Exchange 5.0 : 1459.72
   Exchange 5.5 : 2110.00

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.0.

This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K

A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.