04.dk has no MX records.
Question and response
Question
dig 04.dk. MX
Answer
The response has no answer records.
Authority
04.dk. 3600 SOA ns1.datahjaelp.net. domains.datahjaelp.net. 2026020503 7200 540 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0