relay.hk.net has no MX records.
Question and response
Question
dig relay.hk.net. MX
Answer
The response has no answer records.
Authority
hk.net. 600 SOA ns1.hk.net. hostmaster.citictel-cpc.com. 2019100804 10800 3600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0