User to User Messaging Design Goals

Privacy - No entity should have access to users messages - only the 2 participating users should have access to the content of their messages.

No entity should be able to censor a user from sending messages to another user and receiving messages from him over the platform.

Platform should guarantee all eventual messages delivery. e.g. a bounded time after a receiver client goes online.

Providers should not have access to messages content.

Providers should not be required to save messages for a long period of time beyond what is necessary to route messages between users.

Users should be able to block other entities from messaging them.