DOCUMENT:Q152955 30-MAR-1999 [exchange] TITLE :XCON: MTA Prematurely Returns Messages w/NDR PRODUCT :Microsoft Exchange PROD/VER:winnt:4.0 OPER/SYS: KEYWORDS:kbnetwork ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Exchange Server, version 4.0 ------------------------------------------------------------------------------- SYMPTOMS ======== A message is returned to sender with a Non-Delivery Report (NDR) after only one attempt at sending from one MTA to another MTA using an X.400 connector. When the MTA on the other side is down, the message is expected to sit in the queue and to be retried based on the settings under Connection Retry Values on the Override tab on the X.400 connector property pages. CAUSE ===== The problem occurs for messages sent to address spaces that have only one possible route, but for which the connector used can be involved in multiple routes for other address spaces. A quick test, (that is, "Does the connector have any alternate routes?") is initially used to decide whether or not to reroute a message. The full reroute processing for a message then uses the actual address space of the message to determine if an alternate route is available. (A connector may be the only route for address space X, but may be one of many possible routes for address space Y). During reroute processing of a message with just one possible route, the route history is kept incorrectly. The second time the message goes through through reroute processing it behaves as though : - this message has just been transferred in. - the message has already traversed the destination MTA. The "Routing loop prevention" function then prevents the message from being routed to the destination MTA; no other routes are available and so the message is returned with an NDR. STATUS ====== Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 4.0. This problem was corrected in the latest Microsoft Exchange Service Pack. 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 Additional query words: ====================================================================== Keywords : kbnetwork Technology : kbExchangeSearch kbExchange400 kbZNotKeyword2 Version : winnt:4.0 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 1999.