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

Results forspf.sendsay.ru

Resolver

Location

TXT

Name	TTL	Value
spf.sendsay.ru	600	v=spf1 +ip4:185.138.180.0/22 +ip4:185.76.232.0/22 +ip4:185.231.48.0/22 +ip4:185.235.28.0/22 +ip4:45.143.84.0/22 +ip4:45.153.28.0/22 +ip4:37.140.216.97/32 +ip6:2a07:b40::/29 +ip6:2a05:5dc0::/29 ~all