Some weeks ago, I’ve come across Delta Chat, whose main thing is “(near) instant messaging using your email”
That left me thinking, has this been attempted before? If not, why? Also, why (besides servers’ limitations as means to fight spam) isn’t this solution used more often, given that e-mail has been a decentralized solution for well over 40 years now?
If you’ve ever looked into email protocols you’d find it’s a nightmare of cludged together solutions piled on-top of each other over decades. It simply isn’t designed for instant messaging.
Here’s a great talk that goes into a bunch of issues with email in general.