If you want to test your SMTP server is working correctly, you can use the telnet feature within Windows. The following guide will walk you through the steps to carry this out.
Telnet to test your SMTP server
Just open up an elevated command prompt then enter these commands in turn:
telnet yourmaildomainname 25
This should then connect to your domain and you will see a message like this:
Then run this command:
This should then give you a 250 response:
Then run this command for your sender address:
mail from: email@example.com
This should give you a 250 OK response:
Then run this command for the recipiant of the email:
rcpt to: firstname.lastname@example.org
Then type data and hit the Enter key. If this has worked, you should get a response with a 250 2.6.0 in there and an email address.