Ever set up a new receive connector in Exchange only to have your device completely fail at connecting to it? I have…
Lucky for you (and me!) it’s relatively simple to troubleshoot SMTP connections using Telnet, to see where exactly the connection is going wrong.
|Troubleshooting SMTP Authentication using Telnet
1) Open a telnet tool on your mail server.
You now need to enter your email and then your password encoded in BASE64.
If you have successfully authenticated the server will return: “235 authenticated”
Enter “MAIL FROM YourUserName@YourDomain.com” (replace YourUserName@YourDomain.com with your email address)
Enter “RCPT TO DestinationEmail” (replace DestinationEmail with the destination email)
Enter “Subject: Test using telnet”
Enter “” (Send a blank line to separate the headers from the message body)
Enter “This is just a test to see if I can SMTP auth from my PC”
The server will return: “250 Message queued”