I have a client that is running SBS 2000, all service packs have been
installed. They are having an issue with sending to one domain - att.net.
This is the only domain that I cannot send mail to. If you click on the
properties of the queue it reports the following message: An SMTP protocol
error occurred. Like I said, there isn't any other queues that is holding
mail, all other queues are empty. If set the server to forward mail to their
ISP mail server all other mail stops going out EXCEPT the att.net. Any help
would be greatly appreciated!

Thanks,
Keith