dns2.tokai.or.jp has no MX records.
Question and response
Question
dig dns2.tokai.or.jp. MX
Answer
The response has no answer records.
Authority
tokai.or.jp. 600 SOA dns0.tokai.or.jp. postmaster.tokai.or.jp. 202508001 18000 300 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0