Certificates? That's a pretty decentralized effort. It works because certs whitelist you. You don't claim to get one until you've been whitelisted somewhere, b

Certificates? That's a pretty decentralized effort. It works because certs whitelist you. You don't claim to get one until you've been whitelisted somewhere, by someone else who has been whitelisted. (Generally). With email we assume the sender is a good actor and then have to run around blacklisting spam. Helped with the network effects but caused untold hassle.