However, I draw the line at "text editor" with Emacs. I have no desire to read my email, paint pictures, or compose music inside Emacs—there are better tools for that.
A few years ago I got fed up with not being able to configure Mail.app to notify me of responses to "watched" threads but nothing else and thought "...I bet the CLI tools would make this achievable."
So, I moved to mbsync for fetching email, not much for indexing the local email directory, and notmuch-mode / Emacs for reading and writing email.
It's head and shoulders above any other email setup I've ever used.
I wish I'd done it years ago.