Glossary definition of IMAP

Also known as: IMAP4, Internet Message Access Protocol, Interim Mail Access Protocol

IMAP (Internet Message Access Protocol) is used for reading e-mail. It supports a hierarchical folder structure rather than the single linear mailbox supported by POP3. The IMAP folder structure consists of an inbox and various other folders that live within the inbox that can be created, altered and deleted You can also browse through message headers without downloading the actual message, saving bandwidth.

IMAP can only be used for reading messages stored in a remote server; it cannot be used for sending. SMTP is usually used alongside IMAP to provide the ability to send e-mail. The full specification for the Internet Message Access Protocol can be found in RFC 2060.

The IMAP protocol is supported by nearly all desktop, mobile and web-based e-mail clients, and is the most commonly used protocol for reading remotely stored mail.