ns1.masterdns.nl has no MX records.
Question and response
Question
dig ns1.masterdns.nl. MX
Answer
The response has no answer records.
Authority
masterdns.nl. 300 SOA ns1.masterdns.nl. hostmaster.denit.net. 2023110701 14400 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0