Mail Transfer Agent (MTA)

A Mail Transfer Agent (MTA) is software that transfers email between systems using SMTP: accepting messages from a source, queuing them, and delivering them to their destination servers. "Message Transfer Agent" is the same term; both are correct. MTAs range from general-purpose servers that route a company's day-to-day mail to high-performance outbound MTAs designed to deliver millions of messages per hour across many IP addresses.