I have a 3 character plus tld domain for this purpose. I used to run my own server with Postfix and Dovecot, I was able to deliver mail and it all worked but Mi

I have a 3 character plus tld domain for this purpose. I used to run my own server with Postfix and Dovecot, I was able to deliver mail and it all worked but Microsoft can do the same thing for less money and effort. The best part of running Postfix was I could add domains and addresses to a denylist and it would bounce the email and the senders server would often put a REJECTED message in their inbox. The email equivalent of slamming the door.