dmail.kt-icc.com has no MX records.
Question and response
Question
dig dmail.kt-icc.com. MX
Answer
The response has no answer records.
Authority
kt-icc.com. 3600 SOA ns.kt-idc.com. dns.kt-idc.com. 2023011801 21600 900 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0