Thanks for the response, Josh.
You're right -- the email field is pre-populated when they click the unsubscribed, but once in a while we'll still get one of these come through.
Would you have a link to a resouce that walks me through this setup?: For instance, you can say if the lead is created from that Form, block them. Or mark them as Lead Source=Unsubscribed and block or filter them out.
Thanks!