XADM: Duplicate Messages are Received When Message is Sent to Large DL and Recipient's Quotas are Exceeded

When a user sends a message to a large distribution list (DL), it is possible for some recipients to receive the message multiple times. For this to happen, most of the recipients in the DL must be over their mailbox quota and not allowed to receive new mail. Also, the message must originate from outside the server so that the message is delivered by the Message Transfer Agent (MTA). Users who are not over their quota and are a member of the DL will receive the message once an hour.

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base: The English version of this fix should have the following file attributes or later:

Component: Information Store



Component: MTA

Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 3.

When the Exchange Server information store is attempting to deliver the message, it will log the following error: At this point, the store builds a list of users who cannot take delivery of the message. After this is completed, the store sends the MTA the object with the list. When the MTA sees this large object, the MTA responds with an "out of resources" error. When this occurs, the message does not get purged from the queue, but rather remains in the queue. By default, the store tracks duplicate message delivery for one hour. When the message remains in the queue for over an hour, the store will again try to deliver this message. The users that can accept delivery of the message will get a second copy. Users will continue to get a copy of the message every hour until the message is manually removed from the queue.

To resolve this problem, both the MTA and the store had to be modified to work together. Both components are required for this to work correctly.