IP blocks; block known spammy strings; bayes spam filters, require PoW, require payment, whitelist pubkeys and their follows, and aggressive rate limiting... or some combo of all the above.
According to requiring payment, do you mean using NIP-57?
Please Login to reply.
Nah, I think you can buy a whitelist entry using Lightning. On nostr.watch you can see some relays use it, see under P2R column.
