smtp

from The Free On-line Dictionary of Computing (8 July 2008)
Simple Mail Transfer Protocol
SMTP

   <messaging> (SMTP) A {protocol} defined in {STD} 10, {RFC}
   821, used to transfer {electronic mail} between computers,
   usually over {Ethernet}.  It is a server to server protocol,
   so other protocols are used to access the messages.  The SMTP
   dialog usually happens in the background under the control of
   the {message transfer agent}, e.g. {sendmail} but it is
   possible to interact with an SMTP server using {telnet} to
   connect to the normal SMTP {port}, 25.  E.g.

   	telnet mhs-relay.ac.uk 25

   You should normally start by identifying the local {host}:

   	HELO wombat.doc.ic.ac.uk

   You can then issue commands to verify an address or expand an
   alias:

   	VRFY [email protected]
   	VRFY postmaster

   or expand a {mailing list}:

   	EXPN c-help

   You can even send a message:

   	MAIL From:<[email protected]>
   	RCPT To:<[email protected]>
   	DATA
   	What is the point?
   	.
   	QUIT

   This is useful if you want to find out exactly what is
   happening to your message at a certain point.

   See also {Post Office Protocol}, {RFC 822}, {sendmail}.

   (1995-10-17)