Are most of these protected by sandboxed iframes? What kind if leak are you talking about? Referer leak? That is easy to fix, but what else? I dont think email

Are most of these protected by sandboxed iframes? What kind if leak are you talking about? Referer leak? That is easy to fix, but what else? I dont think email sender cares about how iframe is rendered. They currently render in a rectangle, and they will keep render in a rectangle.