No, email really is broken (and here's how to fix it)

Use OmniFocus for task management, with a script or rule to move messages to Task status. Add a new iCal/vCard style micro format to specify tasks that you wish to delegate to me. No protocol needed, it is just a request after all. The protocol in delegation resides at the human layer, not the technology layer.

Priority etc in email makes it sound like you want to use the one piece of software to write correspondence while simultaneously managing your projects and to-do lists. Use a to-do list manager for managing tasks, use project management software for managing projects.

There are ways to link the lot together, but using the IMAP server as your go-to resource for everything is not the answer.

But I agree with you on the encryption thing.