Researchers from several institutes worldwide recently developed Quarks, a new, decentralized messaging network based on blockchain technology. Their proposed system could overcome the limitations of most commonly used messaging platforms, allowing users to retain control over their personal data and other information they share online.
This system is federated.
The blockchain means that you can access your encrypted messages even if your server goes down.
you and everyone can access those encrypted messages. You are the only one that can decrypt them, sure, but as others have already mentioned, the history of encrypted messages is almost as bad as the actual content.