On my freemium offering at NostrAddress.com it puts the free requests into an hourly batch before their address is live. It has mostly helped stop bots and bad actors as they don’t get the address immediately and have to wait. On the relay side of things, after the reply guy spam, I introduced nip05 validation on Nosflare. This let you block any event who’s author didn’t have a valid nip05 and you could also block specific nip05 domains. I knew in the future there would be spam bots who would have nip05s. It’s all a cat and mouse, whack-a-mole lol