I keep trying to use not-Gmail, but it still Just Works (my most recent serious foray was Evolution, but I've also tried Thunderbird, mu4e inside of Emacs, and a few other TUI ones).

Not having to worry about syncing, search being excellent, Gmail doing the right thing with linebreaks and word-wrapping and threading, Google Calendar integration, snoozing, the "add attached photo to Google Photos" button. It all works fine and is hard to give up.