ns3.bit-isle.co.jp has no MX records.
Question and response
Question
dig ns3.bit-isle.co.jp. MX
Answer
The response has no answer records.
Authority
bit-isle.co.jp. 300 SOA ns.bit-isle.co.jp. root.bit-isle.co.jp. 2025110100 3600 1800 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0