UAlbany ITS: Email Services - Non Personal (Generic) Unix Access Request

What are IMAP and POP?

IMAP and POP are two popular Internet mail protocols (methods) which enable you to retrieve mail from an e-mail account using software on your local computer such as Netscape Messenger or Microsoft Outlook. IMAP stands for Internet Message Access Protocol; POP stands for Post Office Protocol.

The IMAP protocol allows you to read your mail while it is still on the mail server. This allows you to keep your mail in a central location accessible from any IMAP-configured computer. POP is different in that it downloads your mail to the PC, removing it entirely from the server. This is handy in that you can always read your downloaded mail on the PC, even if the network goes down. However, you won't be able to read your existing mail if you're at a different computer.

In order to use IMAP or POP you must have an Internet connection via Ethernet (a direct network connection) or through an Internet Service Provider. These services will not work using the University's dial-up number.

The table below summarizes some of the differences between IMAP and POP in order to help you choose which protocol is best for you.

Differences Between IMAP and POP

IMAP POP

What does it stand for? Internet Message Access Protocol Post Office Protocol

Are messages kept on the server? YES NO (by default)

Is my account storage quota affected? YES. Any mail folders you create (as sub-folders of your INBOX) reside in your account, and therefore affect the amount of space you use (and the amount of mail you can store). NO. By default, all messages are downloaded to your computer and deleted from the server. Therefore, the amount of mail you can store is limited only by the size of your hard drive.

Can I access my mail from anywhere? YES. Since IMAP keeps all mail in a central location (the server), you can set up IMAP on multiple computers and always be able to see all your messages. NO. POP automatically downloads mail to the local computer, so if you try to set up POP on another computer, you won't be able to see old messages, and newer mail will be out of synch.

How fast is it? Faster: IMAP retrieves only the message headers when you check your mail; it doesn't retrieve the entire message until you actually read it. Slower: POP downloads every message in its entirety to your computer, which can take longer with large messages.

This protocol is suitable for... ... users who want access to all their mail from multiple computers or locations. ... users who access their mail from only one location.

For more about these services, you can contact the Information Technology Services Help Desk (LC-27) at 442-3700.

Back to the UNIX Email FAQs and Guides Page

	IMAP	POP
What does it stand for?	Internet Message Access Protocol	Post Office Protocol
Are messages kept on the server?	YES	NO (by default)
Is my account storage quota affected?	YES. Any mail folders you create (as sub-folders of your INBOX) reside in your account, and therefore affect the amount of space you use (and the amount of mail you can store).	NO. By default, all messages are downloaded to your computer and deleted from the server. Therefore, the amount of mail you can store is limited only by the size of your hard drive.
Can I access my mail from anywhere?	YES. Since IMAP keeps all mail in a central location (the server), you can set up IMAP on multiple computers and always be able to see all your messages.	NO. POP automatically downloads mail to the local computer, so if you try to set up POP on another computer, you won't be able to see old messages, and newer mail will be out of synch.
How fast is it?	Faster: IMAP retrieves only the message headers when you check your mail; it doesn't retrieve the entire message until you actually read it.	Slower: POP downloads every message in its entirety to your computer, which can take longer with large messages.
This protocol is suitable for...	... users who want access to all their mail from multiple computers or locations.	... users who access their mail from only one location.