To those of you pushing for ActivityPub: Webber's trashed it (the initial author) and is working on a way to mitigate the problems of it by implementing incompatible changes, the biggest piece of software claiming to implement it doesn't even implement it (Mastodon), the only piece of software that stays semi-faithful is full of devs who hate it (Pleroma). AP is completely broken for anything but publicly-scoped cont…
Direct point-to-point we can make secure (relatively) yes. You can run your own e-mail server, setup up PGP keys, and once you make it through that usability nightmare, you now have secure e-mail (if you trust your hosting provider) that will probably get dropped as SPAM 1/3 of the time when e-mailing anyone on Google/MS/Yahoo.
There's an interesting case where Mastodon and Pleroma respect and forward delete requests. Say you have a thread started on BigInstanceA and I reply from PersonalInstanceB. Someone from IAC replies to the same thread and B sees it, but A can't because C is banned from A. The reply gets dropped. You now have two conversations not in sync.
Say A deletes the original. B gets the delete request, but C never does, since it's a banned instance from A's perspective and doesn't exist ... even though it has a full copy of the deleted thread.
Deletes are truly fucking silly in the AP world. As much criticism as Zuckerberge gets (and deserves), back in the day he just wanted everything public, and I'm kinda for that too. If I post something online, it's never personal. If I need to talk about something personal, I call a friend, or text them, or meet them in a bar or plan my next vacation to be in their city. Real conversations don't happen in this space.