mail.sammicomputer.co.kr has no MX records.
Question and response
Question
dig mail.sammicomputer.co.kr. MX
Answer
The response has no answer records.
Authority
sammicomputer.co.kr. 600 SOA ns.kornet.net. domain.ns.kornet.net. 2025122300 43200 3600 604800 43200
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0