mx.paulstra-auto.com has no CNAME records.
Question and response
Question
dig mx.paulstra-auto.com. NS
Answer
The response has no answer records.
Authority
paulstra-auto.com. 3537 SOA dns.paulstra-auto.com. hostmaster.paulstra-auto.com. 1623891417 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0