mx01.sendcockpit.com has no CNAME records.
Question and response
Question
dig mx01.sendcockpit.com. NS
Answer
The response has no answer records.
Authority
sendcockpit.com. 3301 SOA dns1.netways.de. hostmaster.netways.de. 2025021401 10800 1800 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0