Hi I am receiving a lot of targeted phishing email and want to block an open relay SMTP servers so that to avoid a newly created SMTP server to send me an email.
I'm not sure if there is a specific configuration for that, if you know certain IP's you would not like to allow emails from you can certainly add them to the HAT Blacklist.
You can also look at implementing SPF, DMARC checks for senders to allow only legitimate emails to come through.
