Hide list information for anonymous users to prevent spambots
Public lists can be visible by anyone, including bots. It can be dangerous to display publicly a list of mailing lists, because bots can scrap these pages to get email addresses to send spam.
A way to prevent it is to disallow unauthenticated users to display whole lists. It does not mean that all lists become private: any user could create an account and see the whole list, but spambots won't make this effort.
I implemented this feature in !621.
I think that only the list index should be protected, and not list detail. Anonymous users could subscribe to a list if they know the name, if permitted. Of course, this feature should be optional and configured in settings.py.
This feature also concern hyperkitty, the associated issue is here: hyperkitty#359