Chapter 2. What Is IMAP?

This chapter looks at what IMAP is and what distinguishes it from other mail access protocols. We discuss briefly where IMAP is now and where it’s headed.

IMAP in a Nutshell

IMAP is a way of accessing electronic mail that is stored on a central server.

Certainly, this statement is true, but there’s more to it than that. More precisely, IMAP is a way to retrieve messages from one or more mailboxes on a central server, without ever having to download a single message to local hard disk. The messages remain on the server at all times.

By design, IMAP was intended to provide the same level of functionality for mailbox and message access and management that exists with a mailbox located on a local hard drive. Consequently, IMAP has server operations, such as “search for messages matching such-and-such criteria,” that are normally associated with mail clients.

You can see the advantages of IMAP very clearly if you work from several computers (e.g., home computer, office computer, and laptop). With IMAP, you don’t have to wonder which computer you were on when you downloaded and read a given message. You know it’s still on the server.

With the right IMAP client, you can do all of the following:

  • Learn when new messages arrive in any of your mailboxes

  • Share your mailboxes with anyone or everyone

  • Move messages from one mailbox to another

  • Mark messages with flags (such as “Important”) that are preserved between IMAP sessions

Another distinguishing feature of IMAP is that, ...

Get Managing IMAP now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.