This is (mostly) a bugfix release. Emacs 26 will have some major goodies, threads being one.
Isn't that so 1990's?
Please I mean no disrespect...I was first exposed to EMACS in the late 80's if I remember correctly and have followed it's growth over the many years since, but I can't help but feel that introducing non-blocking threading is something that should have happened long ago.
There's hacks for some of these, but having threads natively will be really nice.
Mu4e is pretty good in this respect: it offloads most of the mailbox processing work to the `mu` command, which it runs asynchronously. I fetch my email with a system service, external to Emacs.
Planning to write a blog post about this configuration, but in the meantime I am happy to share privately - vsedach@gmail.com