mx0.kcnet.org has no MX records.
Question and response
Question
dig mx0.kcnet.org. MX
Answer
The response has no answer records.
Authority
kcnet.org. 300 SOA kcns1.kcnet.org. kcadmin.kcnet.org. 2018111801 3600 900 2419200 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0