mail.mwjp.jp has no MX records.
Question and response
Question
dig mail.mwjp.jp. MX
Answer
The response has no answer records.
Authority
mwjp.jp. 900 SOA ns.elmc.co.jp. root.elmc.co.jp. 2026030301 900 3600 1209603 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0