Hi all, We've a distribution group structure where the top level group contains a number of discipline groups. Each of the discipline groups contains users and also contains the management group. The management group contains senior users in the domain (one forest - 2 exchange serves) and senior users in an office in an external linux setup. When domain users mail the top level group the external users in the management group get multiple duplicates of the message. Internal management group users get one copy. I've verified that an external yahoo mail account in the management group also recieves multiple copies (excluding the linux office as a fault). If I use the message tracking in exchange I can see it is sending the same MessageId multiple times to the external contacts each with a different InternalMessageId. These seem to be generated by TRANSFER / ROUTING / Resolver entries. I've also verified mail sent from either of the domain exchange servers has the same issue. Any ideas on where to go next would be greatly appreciated. :)

Could you take pipeline tracing and confirm which message is unique and which message getting duplicate?Using Pipeline Tracing to Diagnose Transport Agent Problemshttp://technet.microsoft.com/en-us/library/bb125198.aspxHow to Enable Pipeline Tracinghttp://technet.microsoft.com/en-us/library/bb125018.aspxArun Kumar | MCSE - 2K3 + Messaging | ITIL-F V3

Hi,Please try to clarify the distribution structure.1. Domain A, Domain B, A and B is in one forest,root and child?2. DG1,top level, including domain user and MGs3. MGs including users in domain B and contact for external users4. Users in domainA is contact in domain B, is that true?Besides, please try to verify which group that user who receive duplicated emails is member of? Please try to refer to the article below to enumerate which group one user could be member of. How to enumerate a user's security group membership using Visual Basic or Visual Basic Script http://support.microsoft.com/default.aspx/kb/301916 Regards, Xiu

Hi Arun, Been a nice long weekend here. :) I'll try the pipeline tracing and report back later today.

Ok, pipeline tracking gives me an Original mail and Routing0001 to Routing0005. Original, Routing0001 and 0002 all seem very similar and 0003, 0004 and 0005 all seem similar but with expanded distribution lists (i.e. members of the management group appear as X-Receiver: entries 9 times each.)

Hi Xiu, To clariy we have one MS domian in a single forest and an external Linux site that isn't on the domain. The problem only seems to affect users and contacts with external email addresses. The top level DG = "Team" "Team" = 8x discipline groups and the "Management" group. Each of the 8x discipline groups also contain the "Management" group. Mails to "Team" turn up multiple times for external users/contacts who are in in the "Management" group. Domain members in the "Management" group only get a single mail. I've tried removing the management group from "Team", users still get multiple mails and some external "management" users then appeared to fail to recieve messages set to "Team" when sent to the external "Team" address. Can't remove "Management" from the discipline groups for business reasons.

Hi,After you remove Management group from Team,please try to force DC replic and then restart Exchange System Attendant Services.I think the problem is that we have management group as member of both Team and 8xdiscipline groups. So we may remove management group from "Team"Regards,Xiu