Email Mass Relay Testing

I created an SMTP Server for integration into something else recently.

As part of it, I just setup the test server and have it dump the emails directly to text files for my testing, What I found is some scammers looking for Open Relays, by just connecting and sending.
They confirm by putting the details about which server in the email and send it to a few verification email addresses.
For Example:

["From":"test@test.com](mailto:"From":"test@test.com)"
"Subject":"test smtp 1xx.1xx.1xx.1xx-"
"To":"evanscole824@yahoo.com, [tanjacesh@gmail.com](mailto:tanjacesh@gmail.com), [rshaikh@abissaudi.com](mailto:rshaikh@abissaudi.com), [azween@xiddig.net](mailto:azween@xiddig.net)" …

cybersecurity email relay testing