I've created a C3PO (C++) that catches a just sent item and gives the
possibility to move that item to a user created (sub)folder in GW. Basicly
I use therefore the following statement:

pIGWMessages->Move(vMessageID, pDIGWMessages2, &pDIGWMessage);

pIGWMessages belongs to the folder SentItems.

When the move is executed, the message disappears from SentItems. Now it
happens that with some users the message don't disappear, and so exist in
both the destination folder and the SentItems. Perhaps it is an option or
setting in the client, but I cannot find an option like that.

Does anyone has an idea?

Thanks and regards,