Does your mobile website currently use a pop-up message — inviting website visitors to take action? If so, you may be penalized for having pop-ups that interfere with your site visitor accessing information they are seeking. Read on to ensure your SEO rankings are not affected.
Google announced on Jan. 10, 2017, that mobile sites using intrusive interstitials, including pop-ups and full page ads, would see a drop in search results rankings.
Interstitials are defined as pop-ups or full pages that are loaded between two web pages
Common uses for pop-up messages include:
- Email sign-ups for newsletters, ebook or whitepaper
- Related content
- Advertising
- Age or login verification
- Errors or related queries
What does Google call acceptable for pop-ups and interstitials?
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- Showing a popup that covers the main content, either immediately after the user navigates to a page from the search results, or while they are looking through the page.
- Displaying a standalone interstitial that the user has to dismiss before accessing the main content.
- Using a layout where the above-the-fold portion of the page appears similar to a standalone interstitial, but the original content has been inlined underneath the fold.
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–Google Webmaster Central Blog, 1/10/17

Examples of interstitials that make content less accessible; (left) An example of an intrusive popup; (middle) An example of an intrusive standalone interstitial; (right) Another example of an intrusive standalone interstitial
Interstitials that are unacceptable in the eyes of Google
- Interstitials that appear to be in response to a legal obligation, such as for cookie usage or for age verification.
- Login dialogs on sites where content is not publicly indexable. For example, this would include private content such as email or unindexable content that is behind a paywall.
- Banners that use a reasonable amount of screen space and are easily dismissible. For example, the app install banners provided by Safari and Chrome are examples of banners that use a reasonable amount of screen space.
–Google Webmaster Central Blog, 1/10/17

Examples of interstitials that would not be affected by the new signal, if used responsibly; (left) An example of an interstitial for cookie usage; (middle) An example of an interstitial for age verification; (right) An example of a banner that uses a reasonable amount of screen space
Even though your use of pop-up messaging or full-page ads may increase email subscriptions or downloads of your latest ebook, using them might mean you sacrifice the ability of your website being found in the first place. To make sure your website complies with Google, read the entire article on the Google Webmaster Central Blog. Google first announced their intention to penalize intrusive interstitials in Aug. 2016.