facebook_session.user.email = nil?

Question

I'm using authlogic_facebook_connect plugin on my RoR app. Looking to get extended permission from the user to acquire their facebook email address so that I can use this email to store in the database as their "myapp.com" registration email. This way a user can come to the site and click on the facebook connect button and be automatically signed up with my site as well. I know that I need to ask the user for their permission before I can get their facebook email, but I can't find anything around on how to do that.. (fyi I've tried simply getting email from facebook_session.user.email, but of course it's nil due to the permission restrictions)