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

Results forspf-b.rjf.com

Resolver

Location

TXT

Name	TTL	Value
spf-b.rjf.com	3600	v=spf1 ip4:208.235.248.20 ip4:72.20.106.0/24 ip4:68.171.150.128/26 ip4:68.233.76.0/23 ip4:69.27.230.0/24 include:ipreomail.com Ip4:54.240.9.0/18 Ip4:167.89.123.50 include:_spf2.mailgun.org ip4:184.173.153.0/24 Ip4:167.212.1.6 ~all