ns4.mijndnsserver.net has no MX records.
Question and response
Question
dig ns4.mijndnsserver.net. MX
Answer
The response has no answer records.
Authority
mijndnsserver.net. 7200 SOA ns1.mijndnsserver.nl. hostmaster.mijndnsserver.net. 2025032601 28800 7200 2419200 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0