How can you stop duplicate e-mail messages? I had this problem for several years, and it is getting to be extremely frustrating and very time consuming. I had this problem with my iBook G4, running OS X 10x (Tiger). And now I'm having the same problem with my new MacPro 2.93GHz, running OS X 10.6.2 (Snow Leopard). I use only Apple Mail. I really would like to get to the bottom of this very annoying issue .... I tried removing the plist file, but that didn't work for me. When I reopened mail, I was at the set-up screen, and had to set-up my mail from the beginning. That is not the solution, so I had to replace the new plist file with the old one to access my mail again.