_spf.zimpel.de has no MX records.
Question and response
Question
dig _spf.zimpel.de. MX
Answer
The response has no answer records.
Authority
zimpel.de. 18000 SOA ns8.colt.net. hostmaster.newsaktuell.net. 2022064066 28800 7200 604800 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0