mx1.myshoptet.com has no CNAME records.
Question and response
Question
dig mx1.myshoptet.com. NS
Answer
The response has no answer records.
Authority
myshoptet.com. 300 SOA ns1.myshoptet.com. hostmaster.myshoptet.com. 1772356111 1800 3600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0