Mail transport agent - Definition and Overview

A mail transfer agent or MTA (also called a mail server, or a mail exchange server in the context of the Domain Name System) is a computer program or software agent which transfers electronic mail messages from one computer to another. The MTA works behind the scenes, while the user usually interacts with another program, the mail user agent (MUA), which contacts an MTA for actual delivery of the mail.

The delivery of email to a user's mailbox typically takes place via a mail delivery agent (MDA); many MTAs have basic MDA functionality built in, but a dedicated MDA like procmail can provide more sophistication.

See also

• List of mail servers

MTA as an abbreviation can have other meanings: see the MTA disambiguation page.