The difference between POP and IMAP

The student mail servers at NTNU (called "stud") now only support IMAP. This article is still available for those wanting a brief introduction to the difference between these two most known email-protocols. But remember, at NTNU you must use IMAP.

Protocol

A protocol is a collection of rules. These rules enable two computers to "communicate" using the same set of rules

POP

POP is short for Post Service Protocol, ans is being used to retrieve email to your computer. The special thing about POP, is that the email is downloaded to your computer, the copy on your mail server is deleted, and you can read your email without being connected to the net.

Parts of this is also the problem with POP. If you check your email on a computer lab using POP, your email will be downloaded to this computer. If you later move to another computer, these emails will be unavailable to you. And since most public computers are configured to delete all local files on logout, one can easily imagine how using POP can make your email "disappear"

How to solve this problem

Most email programs have an option called "Leave mail on server". Received mail will then only be copied from your mail server and not deleted. In that way you can retrieve a new copy from the server when changing computer.

IMAP

IMAP is short for Internet Message Access Protocol, and is used for retrieving email. The main difference between POP and IMAP, is that IMAP reads the email directly on the server. They are never downloaded to your local computer. The only thing found locally, is a list over the email available on your server.. You will have to be connected to the internet in order to read your email.

The advantage of IMAP is that you only have one inbox to relate to; the one on your email server. You will not have problems with emails disappearing. Only way that can happen, is if you delete them yourself.

What protocol should I choose?

Use IMAP! POP no longer available at NTNU