mx.subspacedynamics.net has no CNAME records.
Question and response
Question
dig mx.subspacedynamics.net. NS
Answer
The response has no answer records.
Authority
subspacedynamics.net. 261 SOA ns.subspacedynamics.net. hostmaster.subspacedynamics.net. 2025080900 43200 3600 2419200 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0