It’s probably useful to mute/block non-spam by nip05.

But for spam or attacks its a losing game, attackers can change nip05 very fast, and when you receive a post you have to first get the kind-0 profile, then check the domain, those are “expensive” checks and with spam you want to do as little work as possible.

With WoT you can discard a post almost immediately without even checking the signature. Proof of Work on the pubkey is also a very fast check but this has other problems. 

So far I have not found other solutions that don’t require the defender to do more work than the attacker but thats the type of solutions I prefer to implement. 

 Domain names cost money. Mastodon is not spammed in this way because domain blocking works, and it is less work than the attacker. Checking nip05 isn't even that expensive. 

 Plus how is WoT not expensive? You have to fetch a bunch of kind 3s and build a social graph.​ 

 only has to happen once and can be done in background or when phone is charging overnight, updating also. When posts come in you just check against a set, its instant.

But its different for a mobile client vs when you are managing a server, I can see that 

 Makes sense. 

 The many ways to stack via #nostr are wild 

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