mx.coq-10.com has no CNAME records.
Question and response
Question
dig mx.coq-10.com. NS
Answer
The response has no answer records.
Authority
coq-10.com. 3074 SOA dns.coq-10.com. hostmaster.coq-10.com. 1885467940 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0