ns2.hkbnes.net has no MX records.
Question and response
Question
dig ns2.hkbnes.net. MX
Answer
The response has no answer records.
Authority
hkbnes.net. 300 SOA a1-138.akam.net. sysadm.ns1.hkbn.net. 2211020498 1800 1800 604800 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0