Say you own a
abcd.com and you only want to use it to send and receive email via
firstname.lastname@example.org. You don't want to provide any kind of website.
Can you set up the DNS records to include an "MX" record and no "A" record?
Is this enough for sending and receiving email to work?
Is this valid in terms of whatever standard defines these things?
Edit: To clarify, the mail server (terminology?) would not be hosted on abcd.com or *.abcd.com