Glossary - SomethingWithHorizons/mailserver GitHub Wiki

IMAP (Internet Message Access Protocol)

An Internet standard protocol used by e-mail clients to retrieve e-mail 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 (IMAPS) is assigned the port number 993.

LMTP (Local Mail Transfer Protocol)

Is a derivative of ESMTP, the extension of the Simple Mail Transfer Protocol (SMTP). It is defined in RFC 2033. LMTP is designed as an alternative to normal SMTP for situations where the receiving side does not have a mail queue, such as a mail storage server acting as a Mail Delivery Agent (MDA).

MTA (Mail Transfer Agent)

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. An MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol. (Adapted from Wikipedia)

SMTP (Simple Mail Transfer Protocol)

An Internet standard for electronic mail (email) transmission. First defined by RFC 821 in 1982, it was last updated in 2008 with Extended SMTP additions by RFC 5321.