This is the OptinMonster preview page. Unless otherwise changed, all OptinMonster optin previews will be handled on this page. After post and sidebar optins will be handled in this content section (sidebar will appear here because you can never know what sidebars are enabled and the widgets inside of them). All other popup type optins will function as normal. Some optin settings are overridden for the preview area in order to make the preview experience better.
This is an actual (but private) page of your site, so you are getting an exact replica of what you will see when you finally decide to push your optin live. If you have any questions, be sure to head over to the OptinMonster website for docs, tutorials and support. Thanks for choosing OptinMonster - here's to converting more visitors into subscribers and customers!