nscluster.be has no MX records.
Question and response
Question
dig nscluster.be. MX
Answer
The response has no answer records.
Authority
nscluster.be. 901 SOA ns.nscluster.eu. hostmaster.nscluster.eu. 2026021500 7200 3600 1209600 901
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0