Programming Internet Email

Chapter 11. The Internet Message Access Protocol

In this chapter:

• Using IMAP

• IMAP Commands

• IMAP Sessions

The Internet Message Access Protocol (IMAP) is to POP what Microsoft Word is to Notepad. Where POP simply does one job well, IMAP is big, complex, and powerful. Whether this is good or bad is a matter of perspective.

IMAP was developed as a successor to POP and includes the capability to operate on remote mailboxes. Unlike POP, IMAP mailboxes may be accessed from multiple client machines since the messages themselves may be maintained on the server. This facilitates email access for mobile users, especially if the IMAP server is connected to the Internet.

One can view IMAP as a protocol for remote editing. It allows electronic mail messages to be stored on a remote server and be edited remotely by any number of clients. Mailboxes, too, may be created, manipulated, and destroyed remotely.

The cost for this increased functionality is increased complexity in IMAP-capable MUAs and MTAs, and in the protocol itself. Because of this, many early implementations were quite buggy. Newer versions of IMAP-capable products are now on the market that address most of these concerns, and the future for IMAP looks bright in an increasingly mobile and networked world.