partner.united-telecom.be has no MX records.
Question and response
Question
dig partner.united-telecom.be. MX
Answer
The response has no answer records.
Authority
united-telecom.be. 1800 SOA bayan.ns.cloudflare.com. dns.cloudflare.com. 2396972175 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0