Hi, I've just installed the Microsoft Exchange Server release candidate at the office. I am firmly convinced that the bounce messages Tim just mentioned are from an Exchange server that has not been set up correctly. Things I've noticed: If the client sends a message to an invalid address on the same LAN the server returns an error saying that there is no transport available. If the mail is from an oustide source, the recipient is not recognized. It's really easy to make mistakes because there is no consistency whatsoever between Exchange Server and MS-Mail Server. Brad