It can be anything! An apex, subdomain, or even a URL.

Results forspf.flexmail.eu

Resolver

Location

TXT

Name	TTL	Value
spf.flexmail.eu	3600	spf2.0/pra ip4:37.148.180.0/25 ip4:79.174.133.0/26 ip4:185.18.8.192/26 ip4:178.208.63.128/26 ip4:37.148.179.0/27 ip4:178.208.61.208/28 ip4:176.62.163.112/28 ~all
spf.flexmail.eu	3600	v=spf1 ip4:79.174.133.0/26 ip4:185.18.8.192/26 ip4:178.208.63.128/26 ip4:37.148.180.0/25 ip4:37.148.179.0/27 ip4:178.208.61.208/28 ip4:176.62.163.112/28 -all