spf.dtms.de has no CNAME records.
Question and response
Question
dig spf.dtms.de. NS
Answer
The response has no answer records.
Authority
dtms.de. 1175 SOA ns01.systemhaus.net. dnsadmin.systemhaus.net. 2026022601 900 7200 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0