_spf.netcologne.de has no CNAME records.
Question and response
Question
dig _spf.netcologne.de. NS
Answer
The response has no answer records.
Authority
netcologne.de. 1490 SOA ns1.netcologne.de. hostmaster.netcologne.de. 2026022302 10800 3600 3024000 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0