IMAP is gradually replacing POP as the main protocol used by email clients in communicating with email servers. Using IMAP an email client program can not only retrieve email but can also manipulate message stored on the server, without having to actually retrieve the messages. So messages can be deleted, have their status changed, multiple mailboxes can be managed, etc. RFC Code reference: Internet Message Access Protocol - Version 4rev1 .
Internet Message Access Protocol. A protocol that enables remote management of mailbox and e-mails stored on an e-mail server. Contrary to the de facto standard (that is POP3), IMAP doesn't require messages (e-mails) to be downloaded to a local machine. You can use your favorite e-mail editor and work on mailbox and e-mails as if they were on your harddisk. The latest version, IMAP4, introduces additional features, of which the most important is keyword searching across e-mails. Compare with POP3.
(tech) â€” The Internet Message Access Protocol (previously called Interactive Mail Access Protocol) is a protocol for accessing e-mail messages.