RFC7505 defines the syntax and use of NULL MX records for domains that are not configured to receive email.
In such NULL MX records, the priority should be 0 and the target server name set to a . (single dot). I tried to create such a record in the Cloudflare web interface but it fails when adding it with the following message:
DNS Validation Error (Code: 1004): Invalid content for an MX record (Code: 9009)
Maybe I’m doing it incorrectly. Has anyone succeeded in adding NULL MX records? Or is support for them lacking on Cloudflare?
Thanks in advance for any pointers