mail.belbone.be has no MX records.
Question and response
Question
dig mailout.belbone.be. MX
Answer
The response has no answer records.
Authority
belbone.be. 900 SOA ns.belbone.be. hostmaster.belbone.be. 2011103639 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0