mx.thenittanyline.com has no CNAME records.
Question and response
Question
dig mx.thenittanyline.com. NS
Answer
The response has no answer records.
Authority
thenittanyline.com. 3600 SOA dns.thenittanyline.com. hostmaster.thenittanyline.com. 1659134474 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0