nsb.nic.ad.jp has no MX records.
Question and response
Question
dig nsb.nic.ad.jp. MX
Answer
The response has no answer records.
Authority
nic.ad.jp. 900 SOA ns3.nic.ad.jp. hostmaster.nic.ad.jp. 2026022402 3600 900 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0