@paniash @oantolin I’ve been using #emacs #gnus for decades and contributed code to it. It’s a great experience and will work with gmail for instance. It has a ridiculous amount of features.
Sending e-mail takes seconds so it’s not particularly annoying that it happens in the main thread.
People have been talking about using the Emacs threads for parallelizing the article fetch, threading, scoring, and sorting for years but no one has done the work. That first time delay (a few seconds for larger groups, can be a minute or more for huge groups) may annoy you if you value performance very highly but I don’t think it’s particularly bad. It’s worth trying,