dns.hketcmail.com has no MX records.
Question and response
Question
dig dns.hketcmail.com. MX
Answer
The response has no answer records.
Authority
hketcmail.com. 900 SOA host1.cntech.net. webmaster.hketcmail.com. 2026020546 1800 900 1209600 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0