E-mail programs, such as Outlook, Thunderbird, Apple Mail, and Outlook Express, access e-mail from a server in one of two ways: POP (Post Office Protocol) or IMAP (Internet Message Access Protocol). Each method offers different advantages for you and your centrally provided e-mail needs.

Please review the comparison chart below.

Post Office Protocol (POP)
Features	Details
"Offline" mail processing convenience:	E-mail is downloaded to your computer and messages are stored on your local machine. (This is the only place that e-mail exists.) The mail is then removed off the mail server. The "offline" mail processing is convenient to use. E-mail messages are easy to backup after being downloaded to your local machine.
Message management:	You are not able to preview new messages before downloading, nor do you have control over which messages can be downloaded.
Access to Northwestern network:	Minimizes the use of server resources and connection times.
Disk quota usage:	Less likely to exhaust disk space on the server. Once delivered, e-mail messages are stored on your local computer and deleted from the mail server. Note: There is an e-mail quota limit at Northwestern. For more information, please see "New E-mail Disk Quotas Expand Space Allotted to Users.")

Internet Message Access Protocol (IMAP)
Features	Details
Travel convenience:	View all incoming mail stored on the server from virtually any location with Internet access. Ability to use different computers at different times and access multiple mailboxes. Provides for faster access to your messages, especially for those who receive many messages or who keep a large number of messages in their mailbox. Best solution for users who need mobility.
Message management:	All e-mails can be previewed directly on the server. User has complete control over which messages on the server are viewed. Suitable for accessing non-email data; e.g., NetNews, documents.
Access to Northwestern network:	Requires a constant connection to the e-mail server to view and compose messages.
Disk quota usage:	Once read, e-mail messages are permanently stored on the mail server. However, you may quickly run out of disk space. Note: There is an e-mail quota limit at Northwestern. For more information, please see "New E-mail Disk Quotas Expand Space Allotted to Users.")