user.starcat.ne.jp has no MX records.
Question and response
Question
dig user.starcat.ne.jp. MX
Answer
The response has no answer records.
Authority
user.starcat.ne.jp. 900 SOA dns1.cnci.jp. nic.cnci.co.jp. 2021090201 7200 3600 604800 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0