[BerislavLopac]

Real-time email is a contradiction in terms, as (at least for me) being asynchronous is one of the main defining features of email. Essentially any chat app, from IRC to Slack, can be called "real-time" email. To me, the phrase "real-time email" sounds like calling a submarine an "underwater car".

[nine_k]

IMs hit the sweet spot between fully real-time (like the phone) and fully async (like paper mail).

The UI is built for efficient real-time communication, but the underlying data model (the log, notifications, statuses, etc) allows for very easy async communication.

I think someone could make a great product by just adding IM-like UI features on top of an existing email backend. Email is pretty fast these days to work as mostly-instant communication.

[taohansen]

I agree! Check out https://delta.chat. I use it every day for emailing. Subject lines are the ellipsized first words of your body and every message is a new email.