mx1.wurfbaum.com has no CNAME records.
Question and response
Question
dig mx1.wurfbaum.com. NS
Answer
The response has no answer records.
Authority
wurfbaum.com. 104 SOA ns01.domaincontrol.com. dns.jomax.net. 2026020200 28800 7200 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0