odns2.nifty.ad.jp has no MX records.
Question and response
Question
dig odns2.nifty.ad.jp. MX
Answer
The response has no answer records.
Authority
nifty.ad.jp. 3600 SOA odns0.nifty.ad.jp. hostmaster.nifty.ad.jp. 202602260 28800 14400 3600000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0