I've gone from Gnus to Wanderlust finally settling on mu4e. The first two were probably more a gimmick where mu4e actually enables me to get things done.
One of those "gimmicks" has been working great for me the past 20+ years...
Yea, sorry, I should have said gimmick "for me" - they're all excellent applications, it's just that mu4e happened to be the one that better suited my situation.
I use the notmuch extension for Emacs (with mbsync for actually fetching the mail and msmtp for sending) and have been very happy with it.
I know. :) But I was hoping that the Great Emacs Envelopment won't happen.
I wouldn't be surprised if emacs was the original inspiration for Zawinski's Law.
Particularly since he has done so much for emacs and email.