biz.kpn.net has no MX records.
Question and response
Question
dig biz.kpn.net. MX
Answer
The response has no answer records.
Authority
biz.kpn.net. 3600 SOA ns1.kpn.net. zonemaster.kpn.com. 2020081801 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0