_spf_internal.easybill.de has no CNAME records.
Question and response
Question
dig _spf_internal.easybill.de. NS
Answer
The response has no answer records.
Authority
easybill.de. 3629 SOA a.ns14.net. server.easybill.de. 2026010605 43200 7200 1209600 14400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0