This is perhaps the most simple and classic opt-in form. When this form is enabled, it places an opt-in box at the bottom of your posts and pages. If a visitor has enjoyed your post and read the entire thing, they will be greeted with a chance to subscribe when they are finished. This is a great way to capture your more attentive readers. These opt-ins can be placed site-wide, or they can be targeted to specific posts or post types.