I have a few users, who are also Blackberry users, that occasionally have duplicate emails generated from their "mailbox". I put mailbox in quotes because I'm not exactly sure where the duplicates are created.

One of these users is in non-cached mode, and the other is in cached mode, and both experience the problem. In fact, the non-cached mode user was originally experiencing the problem while in cached mode, and I made the switch a few weeks ago to attempt to solve the problem. Today I discovered the issue still exists.

I'm not sure if the fact that they are blackberry users could be causing the problem at all. I don't see how, but felt I should mention it anyway.

Does anyone have ideas on how I might begin to troubleshoot this? I can see in the non-cached user's mailbox "Sent Items" that the message was sent only once. I confirmed the message does not state that there was a conflict and in fact that makes sense because they are in non-cached mode.

On the server, we have a mail journaling feature turned on for our third-party mail archiving system, and I can see that that system sees two sent messages. And likewise, the recipient does in fact have two messages in their inbox with consecutive message IDs ([email protected]) and ([email protected]).

It would seem to me that the duplicates are generated on the client, but is there a way to tell for sure?