Comment by fc417fc802

Doesn't the spam filtering complaint apply in equal measure to _any_ E2EE messaging solution? Signal can't implement content based filtering either.

Out of band confirmation is similarly universal unless you're okay with either TOFU or delegation. (Delegation being recursively subject to the same choice.) TLS on the web goes with delegation and a root certificate store obviously.

My point being that none of this is specific to either email or federation more generally.