Unable to send through Outlook XP

[Brian]

Without all the details, it could be that your Outlook is
trying to send the mail in and Exchange format rather than
the more generic internet mail (SMTP).

I'm working under the assumption that this is not in a
corporate environment that is running an Exchange server.
If this is the case, then your mail settings, in the
control panel should not have an Exchange server
configured. If it does, try installing a POP3 server with
your settings, and remove the exchange server.

Hope that helps, I'm making a lot of assumptions, so good
luck.

Brian