What's the difference between POP and IMAP?

If you are checking your email from multiple locations/devices, use IMAP on all devices/locations.
If you are checking your email from a single location, use POP.

POP3, or "Post Office Protocol", can be thought of as a "store-and-forward" email protocol. When using POP mail clients, your email messages are transferred from the email server to your computer's hard drive and then automatically deleted from the server.  POP3 is one of the oldest protocols, and was designed for the situation where mailboxes on the server were small and users were checking their mail from only one computer.

IMAP, "Internet Mail Application Protocol", allows you to read your mail from multiple computers while leaving the messages on the server. Getting your email via IMAP is especially handy when you use several computers or if you travel a lot.  IMAP lets you access your mail from multiple computers - it's always available, because it's always on the server.  IMAP also lets you set up sub-folders where you can move mail that you want to keep so it's available if you need it again but isn't cluttering up your inbox.  IMAP is a newer and more sophisticated protocol, and we recommend it over POP.