IMAP

Abstract

IMAP, the Internet Message Access Protocol, is similar in concept to the POP Protocol described in Chapter 11. IMAP, however, is a much more robust and powerful protocol. In addition to supporting all the features of POP, IMAP also supports the following:

• Multiple mail folders, not just the user’s inbox.

• Storage of flags (read, replied, seen, deleted) on the IMAP server, reading of stored flags, and sharing of these flags with mail readers.

• Server-side searching for messages. With IMAP, you don’t need to download messages in order to search them.

• Server-side copying and moving of messages between folders.

• Ability to add new messages to a remote folder.

• Persistent unique message numbering, making possible synchronization with a server, client-side message filtering (letting you delete the appropriate message from the server later), and multithreaded clients.

• Shared and read-only folders.

• Some IMAP servers can present nonmail sources (such as Usenet news) as mail, which clients can specifically request.

• Some IMAP servers support storage of mail in nonstandard locations, which clients can specifically request.

• IMAP clients can selectively download certain parts of a message—for instance, only a particular attachment or only the message headers.