How to Telnet a Server SMTP

SMTP is used to route email.

Simple mail transfer protocol (SMTP) is a communication language used by email servers. The SMTP protocol relays outgoing mail and routes it to the next email server in the email's communication path. You can send email directly from an SMTP server using the telnet application included with your Windows computer. The telnet application is a command-line based application used to connect to server ports.

Instructions

1. Click the Windows Start button and select "Run." In the text box displayed, enter "telnet server 25" and press "OK." Replace "server" with the name of the SMTP server on your network. 25 is the port number for the SMTP server.

2. Enter "EHLO test.com" to register on the SMTP server. Replace "test.com" with the domain for the SMTP server. The SMTP server responds with your IP address and a prompt ready for your email commands.

3. Type "mail from:[e-mail]" into the telnet prompt. This sets the "from" address users see when you send the email.

4. Type "rcpt to: [e-mail]" into the telnet prompt. Replace "[e-mail]" with the recipient's email address.

5. Type "data" into the telnet prompt. This starts your message. Type your message into the telnet session. When you are finished with the message, click "Enter" then type "." into the next line and press "Enter" again. At this point, the SMTP server sends the message to the recipient.

6. Type "quit" into the SMTP telnet session. This closes your session and shuts down the telnet application.

References

• Microsoft: Telnet to Port 25 to Test SMTP Communication