mail.stellarhosting.dk has no CNAME records.
Question and response
Question
dig mail.stellarhosting.dk. NS
Answer
The response has no answer records.
Authority
dk. 108 SOA b.nic.dk. tech.punktum.dk. 1772011081 600 300 1814400 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0