I have a wordpress page that is created when I do offline events. I take pictures of these people and they are directed to the website in order to view the pictures and they must submit a password they were given offline. I get about 100+ visitors to each page, and I would like to start building an e-mail list of these people. Is there a plugin that is recommended or a method I can use to force people to enter their e-mail address before they access the page? In order to avoid fake e-mails, I'd like to force them to e-mail verify before being given access. Can anyone suggest?