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POP and IMAP Information and Recommedations

This page gives basic background on POP protocol vs. IMAP protocol email handling for Simon's Rock users. As of March 2012, ITS is considering phasing out POP support on our mail server in the near future. (See the Help Page for specifics on setting up your email client program to actually get your mail.)

Current Recommended Practice for Mail

Use IMAP, and, Put Everything On The Server. Everything: Sent mail, Mail you want to keep (possibly sorted into many folders on the server), Junk mail that is detected but not yet deleted, Draft messages, Trash. EVERYTHING on to the server.

This will be an advantage right away if you check your mail from more than one location and like having everything available; also, it will allow ITS to backup all of your stuff automatically.

Having the Trash and Junk live on the server (which may seem non-intuitive: Why clutter the server with that stuff?) has the advantage that it means all of your clients can easily tell which messages are garbage. If Trash and Junk are real mailboxes on the server, when you put something into Junk, every client knows what it is. You'll only need to assign an email to the dustbin once, no matter how many different computers you view your mail from. (DO, however, set your clients to automatically empty these refuse folders every week or so.)

In addition, having everything simplifies the process of upgrading your computers, because all your mail just stays put. Longer term, mail on the server can more easily be available for future magic email gizmos. Most of our desktop computers are not available on the network from off campus, so if your mail lives on your desktop, you probably won't be able to reach it from outside.

NOTE: If you are have been using POP, or have been using IMAP with your mail stored on your local disk, you may wish to ask ITS for assistance in transitioning to IMAP with everything on the server.


Our email server is online 24x7 to accept all email addressed to all users, and to put the received mail into each user's mailbox.

POP and IMAP are two different protocols used by email client programs on the user's computer to get the user's mail from the email server. The server will always hold mail until a client program checks for it; the primary difference between POP and IMAP is how the mail is stored on the mail server after the user has checked it.


The POP protocol was designed back when most email users connected to their mail server (usually at a paid Internet Service Provider) via a slow dial-up telephone modem connection. The primary goal of POP were to get all the mail off of the ISP's server and on to the users' home computers as quickly as possible.

The user could sort the received mail into folders on their home computer, and could keep copies of sent mail on their home computer.

Advantages of POP are that it may be faster than IMAP over slow dialup connections, especially if the user has lots of messages in their Inbox or left on the mail server; also, some very old email clients (e.g. Eudora on Mac OS 9) do not handle IMAP.

Disadvantage of POP are that mail is scattered to all the clients, so it is not possible for ITS departments to do central automatic backups for all their users; also, if users check their mail from more than one computer, it is not possible to keep all the different mail programs synchronized, so they will see the same messages as new multiple times, and copies of sent mail will only be available on the specific computer that sent it.


The IMAP protocol was written to overcome some of the limitations of POP, at the cost of more server space being required. It has become prevalent in college and business settings where the email service providers are willing to provide long-term storage for their users' email, and where many users have access to multiple computers. Since the email is expected to be kept on the server, the IMAP protocol allows the users to create folders and sub-folders to organize their mail on the server, and to mark mail on the server as read or unread.

Thus, the advantage of IMAP is that a user can view mail on the server different client computers, with each having a consistent view of all of the stored messages. If a messages is read from any location, it will be marked as read, and if new folders are added and mail is sorted, the same organization can be seen from the other locations. (However, since most IMAP clients have a user selectable option for keeping sent mail on the server, if this option is not chosen on all of a user's mail programs, IMAP can have the same disadvantages as POP for sent mail.)

Another advantage is that IMAP mail stored on the server can be backed-up to tape daily.

Disadvantages of IMAP are that it requires more storage space on the mail server. For this reason, it is a good idea to regularly delete un-needed and junk mail (and to empty your trash). Moreover, if you have large attachments that you wish to keep, you might download them to your local disk, and then delete them from the server. (On the other hand, if it stays on the server it is automatically backed up. If you download important documents, be sure to back them up yourself.)

Another potential disadvantage is that since all of your mail is kept on the server, it might be more visible if some potential intruder gets into the mailserver than would mail moved to your local machine with POP. Mail on the server can potentially also be requested through a government warrant; if the mail was on your PC you would certainly know if the government was attempting to audit it. However, if users have strong concerns about unauthorized data access, it probably makes more sense to encrypt sensitive data with software such as PGP than to give up the other advantages of IMAP.