Comment by Almondsetat
Comment by Almondsetat 2 days ago
A protocol can only support, never mandate. If I send you "DELETE MSG #4829" and you do nothing and reply with "200 OK; DELETE MSG #4829", nobody observing the protocol's messages will ever know what happened. Sure, an omniscent being could say "but he internally broke protocol, he didn't delete the message!", but by definition if something cannot be verified inside the protocol, it is outside of protocol.
Sure.
In practice, in federated networks bad actors end up being blacklisted. It does not provide any "formal" guarantee, but… it tends to work fine enough. For this specific "deletion request" feature, of course it should always be seen as a convenience thing, and absolutely not about security.
As with many engineering things, it's tradeoffs all the way down. For instant messaging, a federated approach, using open protocols, offers what I value most: decentralisation, hackability, autonomy, open source. My options in this space are Matrix or XMPP. I have not attempted to self-host a matrix server, but have been very happy with my [prosody](https://prosody.im/) instance for almost a decade now.