Recently, a site of mine was rejected due to "Login Only":

"Login Only: During our review of your website, we found that the majority of pages on your site are behind a login, or there is restricted access. Please note that we will not approve applications for login-protected pages, as we are not able to review their content for acceptance into the program."

Although the site does require login to send content, it doesn't require any to view any page. How do I tell the Googlebot or whatever is used to crawl pages to adsense that all the content is publicly available but registration is needed to post?