smtp.truelink.dk has no MX records.
Question and response
Question
dig smtp.truelink.dk. MX
Answer
The response has no answer records.
Authority
truelink.dk. 3600 SOA dns1.cscdns.net. hostmaster.cscdns.net. 2018082354 10800 5400 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0