Skip to content

Instantly share code, notes, and snippets.

@sheikhwaqas

sheikhwaqas/test-email-via-telnet.md

Created December 12, 2024 11:28
Show Gist options
  • Save sheikhwaqas/93ebe965b85b5de15bfb2850cd3b5227 to your computer and use it in GitHub Desktop.
Save sheikhwaqas/93ebe965b85b5de15bfb2850cd3b5227 to your computer and use it in GitHub Desktop.
Download ZIP
How to Test Email Deliverability via SMTP Server using Telnet
Raw
test-email-via-telnet.md

Step 1: Ensure Telnet is Installed

  • On Windows:
    • Go to Control Panel > Programs > Turn Windows Features On or Off
    • Enable "Telnet Client"
  • On macOS / Linux: Telnet is usually pre-installed. It can be used by using the telnet command

Step 2: Open telnet

  1. Open your command line / terminal
  2. Connect to the SMTP server using:
  • telnet <SMTP Server Address> <Port>
  • For Example: telnet smtp.gmail.com 587
  1. Expect a connection message: For Example: 220 smtp.gmail.com ESMTP Postfix indicating the connection is successful

Step 3: Initiate SMTP Communication

  1. Identify yourself HELO <domainname.com> For Example: HELO example.com
  2. The server should respond with 250 OK

Step 4: Authenticate (if required)

  1. If authentication is needed, use: AUTH LOGIN
  2. Provide the base64-encoded username
  3. Provide the base64-encoded password
  4. If successful, the server will respond with 235 Authentication successful

Step 5: Send the Email

  1. Start the Mail Transaction
  1. Specify the Recipient
  1. Start composing the email
  • DATA
  • Response: 354 End data with .
  1. Enter the Email Body
  • End the email with a period (.) on a new line
Subject: Test Email
From: [email protected]
To: [email protected]

This is a test email sent via Telnet.
  • Response: 250 OK

Step 6: Close the Connection

  1. Exit the SMTP session
  • QUIT
  • Response: 221 Bye
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment