Earlier quoted context omitted.
Email allows just enough delay for antispam to do its work in, plus a whole range of antispam solutions involving backoff. Chat requires much lower latency. Any federated/distributed chat system would have to deal with spam and abuse upfront in its design, or people would just migrate back towards controlled systems without those problems. There's a second issue of where the chat continuity should be kept across devi…
> Email allows just enough delay for antispam to do its work in One solution is to only check for spam if the sender is not in your address book. And with chat, you usually have to allow somebody in your address book.
In a modern system, you'd probably want encryption and authentication of who you're talking to. Which is great except now you have to do key management, god help you.