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?
As I used to say to customers of the ISPs I worked for, Internet e-mail was not designed to be instant, and it’s largely good fortune that it works fast enough most of the time.
It would be closer to IM if everyone in the conversation was on the same mail server, which is what often happens within a large organisation, but even then there are overheads that expect there to be a sending and receiving server if not a lot of other things along the way. And as soon as someone outside that organisation needs to be included, their mail system could introduce a bottleneck even if there’s no bottleneck at the sender’s side.
Instant messaging tends to be far more streamlined and centralised precisely so it can be quick.