Every .dk domain that delegates its _acme-challenge name to us13-50f290e1-6dbd0377b80f7b89ff09cf6fe.pages.mailchi.mp. Such CNAMEs hand DNS-01 certificate validation to a shared service, so this list shows who issues TLS certificates through it. Data comes from our own scanners, which re-resolve every .dk domain in the zone roughly once a week.