mx.amatukami.net has no CNAME records.
Question and response
Question
dig mx.amatukami.net. NS
Answer
The response has no answer records.
Authority
amatukami.net. 1049 SOA dns.amatukami.net. hostmaster.amatukami.net. 1540297737 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0