_spf.materna.de has no CNAME records.
Question and response
Question
dig _spf.materna.de. NS
Answer
The response has no answer records.
Authority
materna.de. 3600 SOA rigel.Materna.DE. hostmaster.Materna.DE. 2026022601 3600 7200 2592000 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0