mx03.mail.yinzcloud.net has no CNAME records.
Question and response
Question
dig mx03.mail.yinzcloud.net. NS
Answer
The response has no answer records.
Authority
yinzcloud.net. 3160 SOA ORION.NS.NOVA53.net. SOA.NOVA53.net. 2026021423 10800 3600 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0