ns02.key-p.co.jp has no MX records.
Question and response
Question
dig ns02.key-p.co.jp. MX
Answer
The response has no answer records.
Authority
key-p.co.jp. 1800 SOA ns01.key-p.co.jp. root.ns01.key-p.co.jp. 2023021301 3600 14400 3600000 1800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0