mx0129.ppsmtp.de has no CNAME records.
Question and response
Question
dig mx0129.ppsmtp.de. NS
Answer
The response has no answer records.
Authority
ppsmtp.de. 1569 SOA ns1.p68.dns.oraclecloud.net. hostmaster.ppsmtp.de. 294 14400 1800 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0