mail.vautron.de has no CNAME records.
Question and response
Question
dig mail.vautron.de. NS
Answer
The response has no answer records.
Authority
vautron.de. 300 SOA nsx.nsserve.de. noc\@nsserve.de. 1 300 225 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0