> Or client-side like a personal rspamd

> Or as per-user on server profiles like sieve?

> There could be several competing filters, all of which could be adjusted by user to varying degree.

> Some filters could be learning ones and some could be for special cases (like child filters). There would be no single point of attack, and therefore harder to do social engineering by manipulating the feeds.

This is precisely what we're trying to propose in the original article :)

In terms of UI, visualising the filters could be as simple as "98% of the rooms in this list have been hidden by your #nsfw filter", letting you peek behind the filter to see what you're missing, etc.