using outlook thru proxy

I have a small network that uses an NT server and the clients are Win 98 or XP. We access the internet via Analog X's proxy software and a dial up connection. Analog's software is a simple and free. However, I have not been able to get Outlook Express to work on the client machines. This has been OK since the company email is handled through the machine that has the internet connection. I now have a need to have all (9) clients use their outlook programs. I do not have nearly as much experienceas most of the folks here so can you tell me what my options are? Are there intuitive software solutions? Thanks for your help