Got exactly the same one :)

Would it be possible to set a small bond before using nostr:npub1dd0y8sxhdek6j3nh89vr5yehndeg5w845e52npq9dfwukshag8qqg9r47g to contact me? If I won't mark it as spam the sender gets it back - otherwise they lose it?

I get that done companies might need willing to use it but this would make sure it can't be abused... But on the other hand it could be handheld client side - only display messages sent with some bond paid - spam gets discarded.