WordPress Email Verification & Protected Access

We have an existing WordPress website built with Colibri and need to add verified-email access to a group of existing pages and resources. Goal Capture a valid, verified email address from every visitor before giving them free access to the protected content... (Budget: $10 - $30 USD, Jobs: Email Marketing, HTML, Mobile Development, MySQL, PHP, Web Development, Website Design, WordPress, WordPress Plugin, Workflow Automation)