Required Login to Outlook 2003 Using RPC over TCP/IP

[Kodi]

OK here's the deal. We have Exchange 2003 running on Windows 2003. Our PC's
use Outlook 2003 to connect. We are set up to use RPC over HTTP.

We are setup using basic authentification

What I'm curious is that all of the users are set up identical and are all
required to log in when opening Outlook using domain\username + Password
EXCPET one user who for some reason can log right into outlook without out
having to login.

How is a single user who is set up identical able to bypass this AND how is
this done?

Thanks