An external NDR message is sent to all recipients on a distribution list in Exchange Server 2007 Service Pack 1

On a computer that is running Microsoft Exchange Server 2007 Service Pack 1 (SP1), an e-mail message comes from an internal relay domain instead of from an authoritative domain. This e-mail message is sent to a distribution list that contains external contacts.

When this occurs, the return path is set to the distribution list's primary SMTP address regardless of the configuration of the delivery report settings.

In this case, if an external recipient generates a non-delivery report (NDR) message in the recipient's messaging system, the external NDR message is sent to all recipients on the distribution list. This situation may cause unexpected message traffic.

To resolve this problem, install Update Rollup 1 for Microsoft Exchange Server 2007 Service Pack 1 on the server. For more information about Update Rollup 1 for Exchange Server 2007 Service Pack 1, see the following Exchange Help topic: For more information about how to obtain the latest Exchange service pack or update rollup, see the following Exchange Help topic:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about internal relay domains and about authoritative domains, visit the following Microsoft Web site: For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base: