From time to time people ask us if the ISN can help determine if an email address is correct. Candidly, we are right there with you, we sure wish it could! It would save us all so much time!
An Email Address is only valid if the Postmaster says it is. The Postmaster is the computer in control of delivering the system. When email was developed it was designed much like a traditional snail mail system. A mailed envelope (snail mail) is only proven to have an invalid address if a delivery could not be made. Email was developed using this same methodology. Thus email still requires a delivery of the message first. The Postmaster determines if email address is valid and then either (a) delivers the message to the recipient or (b) creates a new message and sends it back to you states a delivery failed.
Here’s the challenge, the Postmaster will not talk to anyone he/she only receives email – that is all he/she knows how to do. Therefore there is no way to check to see if that address is even valid on that system. (blah!!)
Here is an example of an email going to robert@mycompany.net. The email arrives and the Postmaster takes the email. He/she then looks at all of the email addresses, aliases (etc) and checks to see if he/she can deliver the mail. In this case the Postmaster would not find the address and send you a mail back stating it could not be found.
Several technologies and systems have been attempted and created to allow for checking of addresses but few have really stuck around. Therefore, for now, we cannot check the validity of the addresses in the ISN due to limitations well outside our control. If the possibility emerges in the future we will be in line to jump on the system quickly!
