After almost a year of peaceful and enjoyable existence, my Ning site is now being deluged with requests to join, and all of them are obviously fake gmail addresses. I mistakenly let the first one join, and they immediately started posting links to drug and porn sites. I suspended that person and deleted the contents, and now I have to check every day for other spammers trying to join. Is there anything I can do other than suspend and flag them as spam? Can I block people like this from even applying to join? What does Ning do to verify the validity of people wishing to join a Ning network?