mx1.jd1.de has no CNAME records.
Question and response
Question
dig mx1.jd1.de. NS
Answer
The response has no answer records.
Authority
jd1.de. 10670 SOA ns.jd1.de. hostmaster.jd1.de. 2025120701 28800 7200 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0