For people who don't care about their online anonymity, their computer privacy or their computer security, they're doing fine, they don't care about this issue because it isn't affecting their lives, so forget them, let them use whatever. It would be nice if everyone did safe computing and routinely encrypted their messages but this isn't likely to happen with your standard non technical Windows user sending emails in plain text.
Unfortunately when you have to interact with one of these "non technical" people by email you're forced to expose yourself to plain text email by being the couterparty to their communications. I get drawn into plain text clearnet surveillance in the course of living my daily life.
So you are forced to have a "double life", a face for the public and a then your "private" , "anonymous" online communication behaviour.
So what I'm saying is that I don't think there is a solution for the mass market, as was mentioned here >>10693
, people just want to click a button and for it to work. Too complex but let them have it. As technology marches forward people want more and more. They want high definition video streaming over wifi with a single button click, and a shiny fancy GUI. That needs serious computing power and broadband highspeed internet, so you need to get the latest and greatest 4.0Ghz Intel 20 core processor for it to work seemlessly.
Now for people who do care about security, and who want to communicate securely, there is an answer to this problem. Simplicity. We need to go back to the 8bit computer and the simplicity of single tasking, and programs running on basic. Think Commodore 64, Apple ][, Tandy TRS 80. People used that back in the 80s to access BBS services over the phone line so why can't we do this again but this time better? Turn the computer on and its clean ready to take instructions, turn it off and it dumps the memory and your restart. Don't trust the BASIC ROM? Then swap the chip out with your own hands/tools.
A 1Mhz processsor should be enough for sending email over ethernet, or for posting to a message board by HTTP.
I've seen so many 8 bit retro computer projects so this is doable on a personal level and a commercial offering/project could be made available with some effort.