_spf.dooray.co.kr has no MX records.
Question and response
Question
dig _spf.dooray.co.kr. MX
Answer
The response has no answer records.
Authority
dooray.co.kr. 180 SOA ns1.toastoven.net. webmaster.toastoven.net. 2025121501 21600 1800 1209600 180
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0