Can't setup POP3 E-mail on mail client on my MacBook Pro

Question

So this problem is getting really out of hand and I'm not sure what options I have left. So here are the details:
I'm trying to set up my work e-mail (the site host is Network Solutions) with Mail. There seem to be no problems with the online client. I can sign on without any troubles so password and username are correct. I'm using Mail 4.4. I first enter my name, e-mail, and password with no problems. Then for the incoming mail server I do the same, choosing POP, and I get the following message:
"The POP server "mail.companysite.com" (with the proper domain inserted) is not responding. Try checking the network connection, and that the server name is correct. Otherwise, the server might be temporarily unavailable. If you continue, you might not be able to receive messages."
i get this regardless if i put my username as just username or [email protected] and my network connection is fine as my other e-mail accounts (2 gmails set up as IMAP) work just fine. I've tried using different ports other than the default 110. Still the same problem.
An interesting little quirk is that at one point it actually did work, then suddenly without any changes to anything that I could tell, it stopped. When it was working, I had it set up on my iPod touch and even when it stopped on my computer it kept working on my iPod. But that also didn't last as now I can no longer connect or even set it up.
But wait! There's more. I've tried all the different debugging methods I can come up with, including trying to set it up on different e-mail clients, Entourage and Thunderbird, with the same result. Then I eventually tried it on another computer, on a PC running Windows XP, and wouldn't you know it, it set up without a hitch! so this means that my account is properly set up for this. Furthermore, I know it is possible to use an e-mail client on a mac with this domain as one of my coworkers has set it up on Entourage and Mail as well as his iPhone. I have no firewall settings currently on so nothing should be blocking and i've tried it using several different internet connections in different countries (seemingly then it's not a router or modem issue)
Anyone have any ideas? Any and all help would be greatly appreciated! Let me know if there's any more info you would need me to provide.

Answer 1

Create a New User Account, and as that New User try to set up this one account -- as it is POP, set to leave messages on the server after download. If not familiar with setting up a New User Account, see:
http://docs.info.apple.com/article.html?path=Mac/10.5/en/8235.html
This will be a useful test, and is not meant to suggest a permanent switch to the New User Account, but rather a test of the Mail application outside of your normal User Account.
Also in System Preferences/Networks click on Advanced, then Proxies and make sure no proxy selections have been checked.
Ernie
Message was edited by: Ernie Stamper