spf.flexmail.eu has no CNAME records.
Question and response
Question
dig spf.flexmail.eu. NS
Answer
The response has no answer records.
Authority
flexmail.eu. 2264 SOA ns3.combell.net. hostmaster.flexmail.eu. 1765459514 10800 3600 604800 40000
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0