XCON: Duplicate Messages Received by MS Mail Recipients

• Microsoft Exchange Server, version 4.0

SYMPTOMS

Messages sent to Microsoft Mail recipients through the Microsoft Exchange Internet Mail Connector (IMC) can result in duplicate messages. The sent and recv logs show the message is received and delivered multiple times. The number of duplicate copies received by an individual is equal to the number of Microsoft Mail recipients that are on the recipient list.

CAUSE

Any message received by the Exchange IMC has a responsibility flag set. However, the Windows NT, OS/2, and MS-DOS Multitasking Message Transfer Agent (MMTA) products do not understand the responsibility flag, and External delivers the message to each Microsoft Mail recipient that it finds.

WORKAROUND

To work around this problem:

• If the originating system is a Sendmail V8 or IDA Sendmail, set the mail delivery flag to allow a single message for multiple recipients.

• Use of the Microsoft MSMI should also eliminate duplicate messages but this requires replacing existing instances of external with MSMI connectors.

REFERENCE

For more information, see the Sendmail book published by O'Reilly and Associates.

STATUS

Microsoft has confirmed this to be a problem in External.exe version 3.5. 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.