There are several issues that prevent the correct installation of search functions for private lists: - it is only possible to define a single archive search server in pgweb's settings.py, which makes it impossible to define both a public and a private archives server, - there does not seem to be any kind of permissions verifications in pgweb/search/views.py that would allow only users subscribed to a list to search into it.
I've been told that this functionality did not indeed work for postresql.org's private lists.
Yes, this is a known limitation. This is "documented" in a code comment:
def search(request): if not settings.PUBLIC_ARCHIVES: # We don't support searching of non-public archives at all at this point. # XXX: room for future improvement return HttpResponseForbidden('Not public archives')