Ubuntu :: Comcast Email Does Not Work?

This is my first Ubuntu installation, and I sure like its efficiency and speed.

But I can't get access to my Comcast email no matter what I try. I've spent 3 days on this, reading everything I can find, trying all kinds of "solutions," all to no avail.

Comcast email doesn't work, either through Smartzone webmail, or using an email program like Thunderbird or Evolution. All other email (Yahoo, Google) works fine. But not Comcast.

I have managed to get Thunderbird to send emails, but neither it nor anything else receives emails. Using Thunderbird: when trying to login to receive emails with Thunderbird, I get "Host Contacted, sending login information" and then after an extended delay get an error message: "Sending of password did not succeed. Mail server mail.comcast.net responded: invalid username/password".

However, my username and password that I'm entering are correct (they work with a Windows computer and Thunderbird Windows).

I've tried every combination of setup settings suggested by Comcast, and by others (there are lots of combinations), and nothing works.

With SmartZone, I get the login screen and can enter my username and password, but then the screen just freezes with a blank. I've tried clearing cache, cookies, you name it, and it still doesn't work.