telnet yourmailhost.yourdomain 25Once connected, helo . Often you'll need to identify your sending host if you've restricted sending host.
helo yourmachine.yourdomainTell the system who is sending the mail to to whom the message is addressed.
mail from: you@yourdomain rcpt to: testaddress@yourdomainPlace content in the body of the message by entering data on a single line, and terminating the data stream by entering a period (.) on single line.
data some test text .End the session my typing quit on a single line or using the control-sequence identified by the mail host.