dns2.nii.ac.jp has no MX records.
Question and response
Question
dig dns2.nii.ac.jp. MX
Answer
The response has no answer records.
Authority
nii.ac.jp. 86400 SOA dns1.nii.ac.jp. postmaster.nii.ac.jp. 2026021600 3600 1200 604800 86400
Additional
. 0 OPT ; payload 1424, xrcode 0, version 0, flags 0