The email space is always interesting to me. I love seeing new ways of tackling the stream.
About 4 years ago I found a personal email solution in what I thought would be the unlikeliest of places: Emacs.
Emacs + mu4e + mbsync
If you’ve already invested in improving your general text-editing experience (your own Emacs config), you can transfer lots of its benefits onto the email space. For example, use yasnippets for quickly writing frequent/typical responses.
mu4e search is super snappy on my local imap snapshot (works offline), thus enabling quick batch operations.