mail.speedbone.de has no CNAME records.
Question and response
Question
dig mail.speedbone.de. NS
Answer
The response has no answer records.
Authority
speedbone.de. 3342 SOA ns1.speedbone.de. hostmaster.speedbone.de. 2021072219 28800 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0