8.4. Providing IMAP Access to Mailboxes

IMAP is a powerful and full-featured protocol for mail management. But its many features are both a blessing and a curse. IMAP is a great protocol to use: it provides all the necessary tools to store, organize, and mail on a central server. But IMAP's complexity makes it an intimidating protocol to implement: the base IMAP protocol spec in RFC 2060 runs to more than 80 dense pages. IMAP also puts a lot of burden on the mail server. IMAP servers have to support message parsing (to allow the client to download only selected parts of a message), message searching (using a special query language), and the ability to reference messages using two completely different sets of numeric identifiers (message sequence numbers and unique IDs).

This complexity has historically caused all but the most dedicated developers to steer clear of IMAP, settling for the simpler but less capable POP3. So the fact that twisted.mail includes IMAP support is a great opportunity for developers. It makes it possible for you to write your own custom IMAP server, but without having to deal with all the nasty details of the IMAP protocol.