Mailing lists are horrible for people new to a list, as you have no history to search in your inbox and the UI to browse the archives are beyond atrocious. People that have been on the list for decades tend to forget this, and wonder why it dies down
Usually an email archive of the list is available for download, which you can incorporate into your local archive. In case none is available, what I have sometimes done is to ask a resident member (privately) if they can send me their archive.
Good that you can get the archive, it still has a quite high setup cost for people not used to mailing lists compared to visiting a Discourse forum