Every .dk domain whose MX record points to DGRQGGGJSXQCGZ6H7BHPTP76BME66JII33G5PFHVBTVMJDJPFSIA.MX-VERIFICATION.GOOGLE.COM. Mail-server reverse lookups show which organisations share a mail provider and how widely a hosted mail platform is used. Data comes from our own scanners, which re-resolve every .dk domain in the zone roughly once a week.