What is SMTP?

SMTP (Simple Message Transfer Protocol) is an Internet protocol for transporting e-mail messages.

SMTP is part of the application layer of the TCP/IP protocol. Using a process called “store and forward,” SMTP moves your email on and across networks. It works closely with mail servers to send your communication to the right computer and email inbox.

SMTP spells out and directs how your email moves from your computer to your mailserver, the next mail server, and even several computers. Using that “store and forward” feature mentioned before, the message can move in steps from your computer to its destination.

See also:
Wikipedia: SMTP