On our system, EVERY e-mail account acts as BOTH a POP3 and an IMAP account. Really they are just two different ways to read the mail on your account with us.
With POP3, the mail is “popped” off our server and onto your home computer. There’s no synchronizing going on, just copying of mail files from one place to another. In most POP clients, you can choose to leave a copy of the mail on the server, or to delete it from the server when you download it. POPPING is good if you just want to get online, download your e-mail, and get off line again.
With IMAP your e-mail client is constantly connected to our server, and doesn’t make local copies of your messages. IMAP is great if you access your e-mail from lots of different machines, since it keeps all the messages in one place. It’s also good if you have a slow connection, because it only downloads the e-mail headers until you choose to read a whole message. That’s great for deleting spam by just reading the subject line! IMAP needs a constant connection to the Internet the whole time you’re doing your e-mail.