mx-in-005.inxserver.de has no CNAME records.
Question and response
Question
dig mx-in-005.inxserver.de. NS
Answer
The response has no answer records.
Authority
inxserver.de. 184 SOA ns1.bringe.net. hostmaster.bringe.com. 2024110600 86400 7200 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0