Not sure if this is the right place to ask, but since a few days ago the mailing lists that used to be at https://lists.openwrt.org/ have disappeared. Documentation at https://openwrt.org/contact#mailing_lists hasn't been changed.
Who knows where they are now?
To quote the listmaster:
The machine hosting lists.infradead.org and git.infradead.org suffered
a complete disk failure over the weekend; sadly the last backup of the
mailman config was fairly old (May 2018) so the subscriber lists and
archives have been reset to that date, but the lists should be running
again.
I've recreated the new lists which had been created since then.
[...]
The list archives are supposed to be restored at a slightly later date, but the mailing lists themselves are fully working (already).
Based on the message from the list operator, I am undertain if the archives are intact. To me it sounded like the mailing list contents since that last backup in May 2018 were lost:
we can recreate archives if anyone can provide the mailboxes.
Until the "official" archive of the mailing list is recoverd, you can find the contents at a third-party site:
https://www.mail-archive.com/openwrt-devel@lists.openwrt.org/
This very active mailing list.
There seems no mailing list for end users.