OS X Mail woes


I have a DSL connection to the internet. There is a PC box that runs the proxy server software. Alll the macs (running OS 9) on the network are able to use the internet without the problem. There are 2 macs running OSX. The proxy settings have been set up on these. Internet Explorer works fine without any problems. However, no OS X mail application (mail.app, Eudora etc) are able to access mails. I have tried all combinations to get them to work without any effect. Finally I have set up Outlook Express running in Classic and accessing my mails over the proxy server (OE has its own proxy options).
Can any one throw some light on what I am doing wrong or what I should be trying?
The HTTP port for the Proxy server software is 6558.

Thanks in advance.
Could it be the specific ports are closed on these Mac OS X machines ? Port 25 and 110 and maybe the port of the proxy should be openend. Download and install a firewall app like brickhouse (or something like that, on www.versiontracker.com) to open all your ports, maybe this helps.
I have run Brickhouse and opened all the ports. It still does not work.
I ahve no problem accessing the mail (through mail.app) on a dialup connection though. Funny that Outlook Express should work through the proxy but mail.app does not. Even Sherlock and the Software updater don;t work!!!
I have tried makeing the changes suggested. Still no use. Eudora and mail.app can simply not access my pop server or smtp server. The pop and smtp ports on the Proxy server are open (checked using portscan).

The problem is funny. When i ping my proxy server ( There is no problem. however, mail see the proxys server. It just says connecting and then hangs!!

All the ports on the mac are open.

Thanks In Advance

What is the IP number specified as gateway in the networking prefs of those two clients ? And is this indeed your proxyserver ? When you don't tell the OS X clients that there is a proxy (and i believe you can't specify this in mail.app, so you'll have to do it in Mac OS X), they won't know it even exists...
sorry, i just saw you already set up the proxysettings on those two. sorry.

ehhh,... btw, did you do this with an app other than OS X or mail.app ?
I have tried with mail.app and also Eudora. They cannot access mail through the proxy settings. However, IE has no problem and so are other browsers.
I have booted in the verbose mode and noticed that there are numerous messages saying that there is a time out/unable to access the DNS servers. The funny thing is that IE and other browsers are alright!!