How can I pull this off? (Obtain e-mail address)

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?

try aweber for doube optin landing pages

Honestly the easiest way to do this would be to set the whole WP site up as a membership site. You could acquire the email addresses by simply having people have to be members of your blog to see the posts at all. You could still password protect any given post/page, but you could easily have the added capability of requiring people to sign up first before seeing any content.