smtp.mailcloud.dk has no CNAME records.
Question and response
Question
dig smtp.mailcloud.dk. NS
Answer
The response has no answer records.
Authority
mailcloud.dk. 209 SOA ns.scannet2.dk. hostmaster.scannet.dk. 2021092300 14400 3600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0