What Is SMTP?

SMTP is better known as Simple Mail Transfer Protocol. It is de facto customary for e-mail transmissions crosswise the Internet. However, the protocol that is in use in the present day is better known as ESMTP and in the internet language it is defined in RFC 2821. Earlier it was defined as RFC 821 (STD 10). Some of the most important people who contributed to the development of SMTP are Jon Postel, Eric Allman, Dave Crocker, Ned Freed, Randall Gellens, John Klensin, and Keith Moore.

The legal SMTP session is considered to be that connection that takes place between the sender (the client) and the receiver (the server).