If your distro is any Red Hat from 4.2 through 9.0, the pop server that comes with the distribution (and installs via rpm) works fine. I have used all of them without problems.
You may have your configuration goofed up, though - have you run authconfig and enabled kerberos by any chance? If so, run it again and turn kerberos off.
To be honest, though, POP3 is a crappy protocol. You should be using IMAP or better yet IMAPS instead, and I would recommend either Eudora or Pegasus as a client instead of Outlook. If you aren't using an Exchange server as a back end, there is no benefit to using Outlook, it's just a invitation to Email virii.