mail.server-hosting.expert has no CNAME records.
Question and response
Question
dig mail.server-hosting.expert. NS
Answer
The response has no answer records.
Authority
server-hosting.expert. 3257 SOA ns1.ntdns.de. hostmaster.fastit.net. 2025063067 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0