Here is how to send email using Telnet
- Open the cmd prompt.
- Type telnet server.com 25 (where “server.com” is the name of the smtp (outgoing) server of your email provider, such as smtp-server.austin.rr.com). This can be found by checking your account info in the program you normally use for email.
- Type HELO server.com.
- Type MAIL FROM: firstname.lastname@example.org.
- You may get a message saying “250 ok”
- Type RCPT TO: Friend1@anotherserver.com, email@example.com, friend.3three@Someserver.com, etc.
- again, You may get a message saying “250 ok”
- To write the message, type DATA, followed by your message.
- To end the message, put a period on a new line by itself and press Enter.
- Type QUIT to exit Telnet.
Got this info over at wikihow.com