Table of Contents

About

A mail transfer agent or MTA 1) is a SMTP server that receives an email and transmits it to its final destination, the Mail Delivery Agent SMTP server.

MTA is also known as:

  • message transfer agent.
  • or SMTP relay

Basic

If you want to know the base of email, see this page: How does the email system work? SMTP, POP, IMAP explained

Transport / Transmission

An MTA may transport the E-Mail messages:

Transport Type Description
remotely to another server MTA
locally to the Local Delivery Agent (MDA/LDA (that write them into the mailbox)

List

Server

The well-known MTA that you would install on your server are:

Client

Client MUAs (such as mutt, thunderbird, sylpheed, evolution, kmail) hand off newly sent messages to an MTA. 2)