While SPF/DKIM/DMARC are standard, foundational tools to help protect an email-sending domain from spoofing, what about domains that do not send emails?
How do spam or phishing filters treat emails from domains without MX records? If they are checking DNS for SPF/DKIM/DMARC, certainly they also check for MX and score the incoming email appropriately. Do they?
This matters in terms of the level of email spoofing protection that we might need to consider for non-email-sending domains. Do we need to add in a bunch of SPF records for parked domains, for example?