frontend02.mailsafe.dk has no MX records.
Question and response
Question
dig frontend02.mailsafe.dk. MX
Answer
The response has no answer records.
Authority
mailsafe.dk. 300 SOA ns001.dnspilot.com. hostmaster.dnspilot.com. 2016050310 14400 7200 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0