Troy: you might want to use the standard emails (eg, admin@ rather than dns-admin@) for domain ownership - I'd worry that dns-admin@ might be available to users at some domains.

Also maybe apply for a .well-known to HIBP file uploads?

(It's Mike from CertSimple here BTW)

dns-admin@ is probably from the whois record of the domain you checked. The predefined list is only the last 4 addresses that are shown: security@, hostmaster@, postmaster@ and webmaster@.

Nope, the domain's whois doesn't use dns-admin. From the Baseline Requirements for domin control:

> 3.2.2.4.4 Constructed Email to Domain Contact

> i) sending an email to one or more addresses created by using 'admin', 'administrator', 'webmaster', 'hostmaster', or 'postmaster' as the local part