I've used Emacs/GNUS for just shy of your two decades myself. It was Emacs/VM before that. Note, you can incorporate notmuch into GNUS. From the groups buffe

I've used Emacs/GNUS for just shy of your two decades myself. It was Emacs/VM before that. Note, you can incorporate notmuch into GNUS. From the groups buffer I type G G and type some search terms into the minibuffer and get a notmuch buffer of results. I can browse them and if I find one I want I can do C-c C-c to return to the GNUS buffer with threaded context of that message.