Almost all of them. A good example is Dropbox link you send to someone. I could generate this link to a private file in my Dropbox, email it you, and Bing (may)

Almost all of them. A good example is Dropbox link you send to someone. I could generate this link to a private file in my Dropbox, email it you, and Bing (may) index it. https://www.dropbox.com/s/vucien2ns8jktga/denim%20bodywarmer.png?dl=0 https://www.dropbox.com/s/vucien2ns8jktga/denim%20bodywarmer... I doubt many people realise this when they email "private" links...