Term:IMAP [Internet Message Access Procotol]

IMAP is an acronym for Internet Message Access Procotol.

As its name implies, IMAP is a protocol for accessing email messages. This differs from POP3, which is primarily a protocol for transferring (or moving) messages.

When IMAP is used by email programs to access messages stored on an email server, they are left on that server unless explicitly deleted or moved by the user. Copies of email messages may be downloaded, but fundamentally, IMAP provides what can best be termed a window or a view on a collection of email stored on the server.

While copies of email may be downloaded, enabling offline access, the IMAP protocol works best when continuously connected to the email server. Changes on that server – such as new mail arriving, or email being deleted or altered by a web interface or another email program – are quickly reflected in programs accessing that email server via IMAP.

Multiple-simultaneous access – meaning more than one computer or device accessing the same collection of email at the same time – is one of IMAP’s strengths, and it’s often the technology used by mobile devices, and even web interfaces, to manage email that might be accessed from multiple locations. The down side is the more or less constant connection that’s best used, as well as the fact that email accumulates on the email server unless deleted, which can sometimes cause email accounts to exceed storage quotas.

For more, see What is IMAP? And how can it help me manage my email? on Ask Leo!.

See also: SMTP, the protocol for sending email, and POP3, the protocol for downloading mail.

IMAP (Wikipedia)

In computing, the Internet Message Access Protocol (IMAP) is an Internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection. IMAP is defined by RFC 3501.

IMAP was designed with the goal of permitting complete management of an email box by multiple email clients, therefore clients generally leave messages on the server until the user explicitly deletes them. An IMAP server typically listens on port number 143. IMAP over SSL/TLS (IMAPS) is assigned the port number 993.

Virtually all modern e-mail clients and servers support IMAP, which along with the earlier POP3 (Post Office Protocol) are the two most prevalent standard protocols for email retrieval. Many webmail service providers such as Gmail and Outlook.com also provide support for both IMAP and POP3.

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