[ubermonkey]

Absolutely this.

I've seen a bunch of "new takes" on email over the years, but none of them have been interesting to me because I don't want to run my mail on something goofy and proprietary that I can't easily and (mostly) painlessly migrate somewhere else.

Also, I'm not sure email needs a "new take."

[m-p-3]

It would be nice if IMAP received some extensions that makes it more up to par with proprietary mail services

For example, a standardized method that allows you to tell your email server to send an email at a specific time.

[wolco]

That's not IMAP job that is a service on top.