benesse.ne.jp has no MX records.
Question and response
Question
dig benesse.ne.jp. MX
Answer
The response has no answer records.
Authority
benesse.ne.jp. 300 SOA ns1-07.azure-dns.com. root-dns.benesse.co.jp. 2017033050 3600 900 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0