Mail3 is a crypto-native communication protocol that promises security, privacy preservation, and self-sovereign identity. It enables users to capture the value of their social connections and accumulate digital reputation on-chain. Mail3 aims to be the infrastructure for web3 communication and a platform for valuable information such as relationships, reputation, and trust. Thanks to its decentralized architecture, users can directly establish private connections with one another without concern for being monitored or censored. Personal data, social relationships, and their corresponding value are stored in a distributed and permanent manner.