The PopUp generated by the plugin is not a standard PopUp window but rather a lightbox that opens inside the website window, and thus, it is technically not a popup. When the lightbox PopUp appears after a user-configured delay, it will freeze the page your visitor is on, and display the opt-in form while the website is slightly darkened but visible. This focuses the visitor’s entire attention to the opt-in box while the other visual stimuli is suppressed. Pretty ingenious. And, moreover, there is no risk of the PopUp being blocked by PopUp blockers.