IMAP (Internet Message Access Protocol)

A transport protocol for retrieving messages from a mail server, created as an alternative to POP3. IMAP provides flexible management of messages, maintains the connection to the server during the entire session, and downloads only user-selected messages onto the client device. This reduces the response time and the amount of transmitted traffic.

A disadvantage of IMAP is the flawed algorithm for sending outgoing messages; so SMTP instructions are commonly used for this purpose.