mail.preeco.de has no CNAME records.
Question and response
Question
dig mail.preeco.de. NS
Answer
The response has no answer records.
Authority
preeco.de. 600 SOA ns57.domaincontrol.com. dns.jomax.net. 2026021802 28800 7200 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0