@darius XMPP has those abilities. Federation with activitypub (like mastodon) is brand new, but xmpp has always been 'fedetated' across its own servers. There are also gateways to most social networks you could imagine. The 'DM"s van also be end2end encrypted.
@Delib SMTP also has these abilities -- I am asking about fediverse/activitypub. It is frustrating to say "has anyone done X with Y technology?" and to get responses that are "Z technology does this"