XCON: Messages Fail Downgrade, Bounce Between X.400 Connectors

• Microsoft Exchange Server, versions 4.0, 5.0, and 5.5

SYMPTOMS

In some Microsoft Exchange topologies, there may be cases where a message is constantly re-routed. The configuration where this occurs is as follows:

1. There must be at least two X.400 Connectors that the message can be routed to. Typically each connector will have the route c=* in the Address Space tab of their properties page in the Microsoft Exchange Administrator program.

   whose address is in another user's personal address book (PAB).
   The PAB entry has become invalid either because they have been
   deleted from the system or their original Exchange Site no longer
   exists in the organization. If you use the Message Tracking feature
   in the Microsoft Exchange Administrator program, this will show up
   as a Distinguished Name (DN), in other words:

      /O=<org>/OU=<site>/CN=Recipients/CN=<DN of recipient>.

   Event ID: 175
   Source: MSExchangeMTA
   Category: X.400 Service
   Description:
      (MTA DISP:RESULT(23) Proc 147) 11-17-97 01:41:11pm
      Transfer-Out failure, failed to downgrade per-rcpt-info
      X.400 reason code     unable-to-transfer
      X.400 diagnostic code unable-to-downgrade
      MTS Identifier C=US;A= ;P=MICROSOFT;L=JUNWIN03-971117134110Z-4

   Event ID : 287
   Source : MSEXchangeMTA
   Category : X.400 Service
   Description:
      (MTA DISP:RESULT(22) Proc 436) 11-17-97 01:41:11pm
      Successful rerouting
      MTS Identifier    C=US;A= ;P=MICROSOFT;L=JUNWIN03-971117134110Z-4
      New Connector     /O=MICROSOFT/OU=MILTON

      New Target entity /O=MICROSOFT/OU=MILTON

      Old Connector
      Old Target entity /O=MICROSOFT/OU=MILTON

The sender of the message will eventually receive a non-delivery report (NDR) containing the following diagnostic information:

   Either the size of this message exceeds your maximum allowed message
   size or you have exceeded the storage limit on your mailbox.

CAUSE

The message is being re-routed to the other connector, and this looping continues until the diagnostic information on the message eventually grows too big and the message is NDR'ed. The message is routed to the group of connectors that can send the message, but in this case only the 1984 connectors can do this, and they do not have Connected Sites information. The Microsoft Exchange message transfer agent (MTA) cannot downgrade the message to be sent and should NDR it with:

   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 - or use Exchange 4.0 SP5
   Exchange 5.0 : 1459.72 - or use Exchange 5.0 SP2
   Exchange 5.5 : 2110.00 - or use Exchange 5.5 SP1

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 4.0. 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.

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

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5. 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.