OK here we go. I have recently upgraded a client to Exchange 2010 and updated it to rollup 4. I am working downloading and installing SP1 as I type this. The problem we are having is with duplicate message detection. They have a supplier who sends them price updates constantly. When they send updates they send them in two seperate emails. Both emails will have the same subject and body with an attachment of each of varying sizes. The difference is that they are sent 20 minutes apart. The supplier's email server is generating the same MessageID for both emails. I've read on how duplicate message detection works and with the emails having different time stamps they should make it past duplicate message detection and be delivered to the receiptant. But however duplicate message detection is catching the second email and trashing it. I've read the information on duplicate message detection on http://msexchangeteam.com/archive/2004/07/14/183132.aspx and have tried changing the registry entry to as suggested to no progress. Anyone have any more suggestions for me? P.S. FYI I've looked at just about everything link out there to try to fix this.

Are you able to show examples of the message header for two messages with the same message ID? I realise this might be tricky given that Exchange is detecting duplicates, but maybe you can get them sent to to a private (e.g. gmail) recipient. In particular it would be interesting to see the "Date" field as I believe Exchange uses this to determine the submit time. Alexei

Hi, Try to recreate mail.que file and see if the issue persists: 1. On the hub transport server which generate the duplicate messages, stop Microsoft Exchange transport service. 2. Open C:\program files\Microsoft\Exchange server\transportroles\data\queue, rename mail.que to mail.old. 3. Start Microsoft Exchange transport service. Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Thanks Gen Lin-MSFT

Currently we've had another issue come up and I am working with Microsoft on it. Once we get this issue resolved and if problem still exist I will get you the requested information.