I experianced the issue desrcibed above when I used a pop3 client to access email on a server and told the client to leave the mail on the server. The client was not able to distniquish between new mail and mail that it left on the server. I had this problem several years and ago and thought it would be fixed by now guess not. Tell the client to delete the mail from the server when it gets it or live with double mails.

Cheers,
-D