Email Protocols (IMAP vs. POP)	Printer Friendly
Computing Services Information Document	Email

General Information

Internet mail is handled by various protocols. While all of these are designed to deliver your email to you, there are some fundamental differences.

NOTE: At Rutgers, IMAP is highly recommended. Although POP or POP3 may be available, and may even be the default protocol for your email program, you should not use POP/POP3 unless you have a very good reason to do so and clearly understand the ramifications of using POP/POP3.

IMAP

IMAP stands for Internet Mail Access Protocol. The primary characteristic of IMAP is that email messages remain on the server, instead of being downloaded to a local, personal computer.

One advantage of IMAP is realized by accessing email from multiple computers (such as at home, in a public lab, at an internet café and/or anywhere else). Checking email with an IMAP client or a web browser via WebMail keeps the messages on the server for access whenever and wherever needed. IMAP uses folders for email organization, and these folders are kept on the server as well.

Another advantage to IMAP is quicker access to mail. If email is accessed via modem dial-up, an increase in speed should be noticed, since (usually) only the message headers are initially downloaded. It is possible to download, open, and read only those messages that are of interest.

One drawback to using IMAP and saving messages on the server is the restriction of quota limits. Once an account quota is reached (by email and/or other files stored in the account), new email may be returned to the sender.

A final, but important aspect of IMAP is that messages left on the server are backed-up during regular server backup sessions, should any need to be restored at some point.

POP

POP or POP3 stands for Post Office Protocol. This email delivery protocol was the standard for a number of years, particularly when server-side storage space came at a premium. The primary characteristic of POP is that all email messages are removed from the server after they are copied directly to a local, personal computer. This is useful if inconveniently small storage quotas are assigned on the server, or in order to retain all email messages locally so that they can be accessed offline. Once downloaded, email messages that are retrieved with POP can be read anytime without reconnecting to the internet.

The biggest drawback (usually) to POP is that email messages can only be accessed using the computer onto which they were downloaded. This can be a severe disadvantage, since emails downloaded on one computer will then no longer be available via WebMail or for any other computer to download or view.

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