mail.astutium.com has no CNAME records.
Question and response
Question
dig mail.astutium.com. NS
Answer
The response has no answer records.
Authority
astutium.com. 300 SOA ns1.this-dns.net. dns-soa.doesnotaccept.email. 2023043004 1200 900 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0