> And they probably want to reserve usage of their domain for email so you know it's a staff member you're dealing with, which is why google gives away gmail.com addresses, not google.com addresses.
These inboxes would be for your custom domain that you registered, not @cloudflare.com for everyone. I used that for his because it sounds like he works there.
Yours would be x13@whateverdomainyouregistered.com.