Designing a new protocol is the easy part.

But for that new protocol to be useful, it would need to:

(1) become an open standard which anyone could implement, and

(2) be built into every major platform.

For example, if I want to send a message to someone, let's say my doctor, I can't expect them to download some app or create an account on some new web site to be able to read it. E-mail doesn't require that, and any protocol that does would face huge obstacles to being adopted by the general population.

I'm aware of all the points you outlined, which is why I wrote "design something new and everybody got on board in an instant". Perhaps my wording is flawed.

I'm still more interested in the use case. Not what it takes to replace email. Because IMHO replacing it would mean to understand what people actually use it for these days.

I mean email is universal.

Corporate email services, exchange server etc are enormous and integrated into the workflow of hundreds of thousands of the world's largest companies.

> Because IMHO replacing it would mean to understand what people actually use it for these days

You can't replace something so deeply embedded and universally used. You extend it.

Depends on your requirements but, JMAP ( JSON Mail Access Protocol (jmap) ) is on its way.

[1] https://www.ietf.org/blog/jmap/ [2] https://datatracker.ietf.org/wg/jmap/about/