Send email via telnet

A blast from the past! Sending an email via Telnet is a great way to understand the underlying protocol and can be a fun exercise. Here's a step-by-step guide to help you send an email using Telnet:

Prerequisites:

  1. You have a Telnet client installed on your computer. If you're using a Mac, you can use the built-in telnet command in the Terminal app. On Windows, you can download a Telnet client like PuTTY.
  2. You have a working email account with a mail server that allows Telnet connections.

Step-by-Step Instructions:

  1. Open your Telnet client and connect to the mail server's SMTP port (usually port 25). For example, if your email account is with Gmail, you would connect to smtp.gmail.com on port 25.

telnet smtp.gmail.com 25

  1. Once connected, you'll see a prompt like 220 smtp.gmail.com ESMTP. This is the mail server's response to your connection.
  2. To send an email, you need to issue the HELO command to introduce yourself to the mail server. Type HELO your_email_address (replace your_email_address with your actual email address).

HELO your_email_address

  1. The mail server will respond with a 250 code, indicating that the HELO command was successful.
  2. Next, you need to issue the MAIL FROM command to specify the sender's email address. Type MAIL FROM: your_email_address (again, replace your_email_address with your actual email address).

MAIL FROM: your_email_address

  1. The mail server will respond with a 250 code again.
  2. Now, you need to issue the RCPT TO command to specify the recipient's email address. Type RCPT TO: recipient_email_address (replace recipient_email_address with the email address you want to send the email to).

RCPT TO: recipient_email_address

  1. The mail server will respond with a 250 code once more.
  2. To send the email, you need to issue the DATA command. Type DATA to start composing the email.

DATA

  1. Type the email message, followed by a blank line to indicate the end of the message. For example:

`Subject: Test email from Telnet

This is a test email sent using Telnet.`

  1. Once you've finished typing the email, press Enter twice to send the message.
  2. The mail server will respond with a 250 code, indicating that the email was successfully sent.
  3. To quit the Telnet session, type QUIT and press Enter.

QUIT

That's it! You've successfully sent an email using Telnet. Keep in mind that this is a basic example, and you may need to add additional headers or formatting to your email message depending on your specific requirements.