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

Results forspf.outboundrelay.blacknight.com

Resolver

Location

TXT

Name	TTL	Value
spf.outboundrelay.blacknight.com	3600	v=spf1 ip4:81.17.249.0/24 ip4:46.22.139.106 ip4:46.22.139.0/27 ip4:46.22.139.223/26 ip4:46.22.139.106 ip4:46.22.139.218/31 ip4:46.22.139.220/31 ip4:46.22.139.222 ip4:46.22.136.52 ip4:46.22.136.57 ip4:46.22.136.58 ip4:46.22.136.64 ip4:46.22.136.219 ip 4:46.22.136.233/29 ip4:46.22.136.240/29 ip4:46.22.136.249/29 ~all