cpcnet-hk.com has no MX records.
Question and response
Question
dig cpcnet-hk.com. MX
Answer
The response has no answer records.
Authority
cpcnet-hk.com. 600 SOA ns1.hk.net. hostmaster.cpcnet-hk.com. 2018092701 10800 3600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0