A dial-up networking connection to an Internet Service Provider, a POP3 mail server. Note - this program works ONLY on a POP3 mail server. If you don't know what that is, ask your system administrater.
This is a niffty little program that will sit on your system tray, checks to see if you have any mail waiting, and, if you have mail, downloads the headers for you to browse. Allows "QuickView" of messages you double click on (i.e., take a quick look at a select message in your mailbox by only downloading that one!). It's cool, and you know you want it. Use it, and be happy!