mx.na1.hgncloud.com has no CNAME records.
Question and response
Question
dig mx.na1.hgncloud.com. NS
Answer
The response has no answer records.
Authority
hgncloud.com. 28 SOA dns1.p01.nsone.net. hostmaster.nsone.net. 1640064265 43200 7200 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0