What are Gmail Sponsored Promotions (GSP)?
Gmail Sponsored Promotions are advertisements placed in users’ Gmail inboxes as collapsed promotions. They become fully visible only when the user decides to open them. The user, seeing a customizable add-on full screen, makes the view and ongoing payment feasible only when they tap to open it. As stated, these are promoted through the Google Display Network and are available for design through the Ad Gallery part of Google Ads.
For example, promoting a free e-book to the newsletter subscribers. A collapsed ad can show a course preview and retarget previously visited sites.
Related terms: Native Advertising, Display Network, Ad Expansion, Cost-Per-Click