Provocative thesis: email is an example of the failure of federation.
The API is frozen because of the gigantic size of the deployment. The API is inadequate. Spam has destroyed email as a result. We cannot fix it, because getting the API right early didn't happen.
@ceejbot Well, I don't know how you characterise success but it's obviously not by user adoption. And one could argue that it's the only metric worth mentioning.
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!