waves.ne.jp has no MX records.
Question and response
Question
dig waves.ne.jp. MX
Answer
The response has no answer records.
Authority
waves.ne.jp. 600 SOA name.technowave.ad.jp. bind-admin.technowave.ad.jp. 2012082979 10800 3600 604800 600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0