This is one of the easiest ways for relays to cut down on spam, without requiring payment or other complicated schemes.
If you want a relay open only to you and your circle of friends (or friends of #[2] ), all you have to do is configure your pubkey and then follow people you think are quality.
You can widen the network (setting "levels: 3") to whitelist thousands of pubkeys. Or restrict it to just the ones you follow.
End result: spammers will be thwarted!
https://code.pobblelabs.org/fossil/nostr_relay/doc/tip/docs/foaf.md
