For the vast majority of U-M, IMAP is a better choice than POP for checking email. IMAP is strongly recommended if you ever check your email on different computers, if you travel often, or if you wish to keep your email centrally stored on the server.

POP should only be used in locations where IMAP and webmail access are not available. POP is designed to download messages from the server and delete them afterwards. Most email clients have options to leave messages on the server or only delete messages from server when deleted locally, but these are strongly discouraged. Using these options make POP much slower, and consume significantly more server resources. Also, those who use these settings run the risk of exceeding their email space quota, preventing delivery of new messages. POP may also prevent useful backups of your email account, since the messages could be downloaded before a backup copy can be made.

IMAP is designed for optimal online performance, where messages are always left on the server. Many IMAP clients also support disconnected use, where messages are replicated, or cached, on your local computer for offline viewing. IMAP handles large folders and messages with far greater efficiency than POP, and includes the ability to manage multiple mail folders on multiple servers. IMAP is recommended for everyone who wishes to access their inbox and/or email folders from more than one computer, as well as anyone who wishes to leave email on the server for any reason.

Note: No matter what email program you use, regardless of if you use POP or IMAP, you should always make sure your email program is set up to use SSL.