Outlook 2003 – Remote email server using Proxy Server

I have a user that attaches to a remote POP/SMTP email server using Outlook 2003 in addition to the local Exchange server. A change was made in our Firewall that requires all Internet traffic to go through our Proxy server. Now, the user can “maually” log-in to the remote email server, but cannot attach via Outlook. What am I missing in an Outlook setting? HELP!!! Thank you in advance for any input!