nntp://news.public-inbox.org/inbox.comp.mail.public-inbox.meta
https://public-inbox.org/meta/
+And as Tor hidden services:
+
+ http://hjrcffqmbrq6wope.onion/meta/
+ nntp://hjrcffqmbrq6wope.onion/inbox.comp.mail.public-inbox.meta
+
You may also clone all messages via git:
git clone --mirror https://public-inbox.org/meta/