manage-master.xunit.jp has no MX records.
Question and response
Question
dig manage-master.xunit.jp. MX
Answer
The response has no answer records.
Authority
xunit.jp. 300 SOA ns01.xbit.jp. xunit-support.rakus.co.jp. 2022022405 14400 60 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0