XADM: Exchange Server 5.5 User Receives Duplicate E-Mail Message When on Exchange 2000 Server Distribution List and Carbon Copied

When a user's mailbox is located on an Exchange Server 5.5 computer and is a member of a distribution list (DL) that is based on a computer that is running Microsoft Exchange 2000 Server, the Exchange Server 5.5 user may receive duplicate e-mail messages if a message is sent to the DL and the user is carbon copied (cc) on the e-mail message.

To resolve this problem, obtain the latest service pack for Exchange Server 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base: The following files are available for download from the Microsoft Download Center:
For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.

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 4.