d.nsset.be has no MX records.
Question and response
Question
dig d.nsset.be. MX
Answer
The response has no answer records.
Authority
be. 600 SOA a.nsset.be. be-hostmaster.dnsbelgium.be. 1028234530 3600 1800 2419200 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0