mail.synaxon.de has no CNAME records.
Question and response
Question
dig mail.synaxon.de. NS
Answer
The response has no answer records.
Authority
synaxon.de. 3600 SOA dns1.cloudns.net. support.cloudns.net. 2026022804 7200 1800 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0