mgmt.bbtower.ad.jp has no MX records.
Question and response
Question
dig mgmt.bbtower.ad.jp. MX
Answer
The response has no answer records.
Authority
mgmt.bbtower.ad.jp. 900 SOA pdns10.bbtower.ne.jp. noc.bbtower.ad.jp. 2026011901 3600 1200 3600000 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0