< 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 :
You can then issue commands to verify an address or expand an alias:
VRFY email@example.com VRFY postmaster
or expand a mailing list :
You can even send a message:
MAIL From: firstname.lastname@example.org RCPT To: email@example.com 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 .