In my never ending quest to move every conceivable task into Emacs, I came across this Emacs Stack Exchange entry on reading mailing list archives with Emacs. That turns out to be pretty easy to do.
The trick is to use Gnus. Even if you use something else, like mu4e to read your email, you can fire up Gnus to read the mailing list archives. Here’s the TL;DR (although the SE article is pretty short).
First configure an nntp server in your init.el like so
(setq gnus-select-method '(nntp "ger.gmane.org"))
Specify whatever nntp server you use but if, like many, your ISP no longer offers news, you can use ger.gmane.org as I did above.
Then fire up Gnus with 【Meta+x】 gnus and type
B nntp news.gmane.org
At this point you should have a list of all the mailing lists on Gmane. If you’re interested in, say, the Emacs Development list, search for emacs.devel and select it. From there, you can select individual threads to read.
What I like about this solution is that Gnus is built in so you don’t need any setup other than specifying your nntp server. Even better, you don’t have to master Gnus, which is famously difficult. Just follow the steps above and navigate as you would expect.