I found this awesome addon for Firefox that is a POP3/SMTP mail notifier & client for Firefox. It’s called Simple Mail and can be downloaded here. Here’s a preview below.

Tray Icon:

Message Preview:

Plus, you can even add a wav file to make a sound when you have new mail. It’s pretty amazing I think. It beats having to sign in too many times into my web mail from my server. I don’t use Outlook nor so I like it. That’s why this addon is sooooo perfect because it’s right in your browser too!! Cool!!!

The wav file I am currently using to notify me when I get a new message can be found here. It’s called mail 3 and should be the first one on that page.