_spfblockjp.linecorp.com has no MX records.
Question and response
Question
dig _spfblockjp.linecorp.com. MX
Answer
The response has no answer records.
Authority
linecorp.com. 600 SOA ns2.naver.jp. domain.linecorp.com. 1772152766 3538 600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0