mxout01do.versatel.de has no CNAME records.
Question and response
Question
dig mxout01do.versatel.de. NS
Answer
The response has no answer records.
Authority
versatel.de. 4504 SOA dnsdb.versatel.de. hostmaster.versatel.de. 2026010700 10000 3000 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0