Some registrars make this easy. Think it was cloudflare that has a button for "Do not allow email from this domain". Saw it last time I set up a domain that I d

Some registrars make this easy. Think it was cloudflare that has a button for "Do not allow email from this domain". Saw it last time I set up a domain that I didn't want to send email from. I'm guessing you get that question if there is no MX records for the domain when you move to cloudflare.