Gmail is actually a bad example, since spam is "relatively" easy to detect, but detecting fraudulent reviews or behaviours is far, far more complicated. A bette

Gmail is actually a bad example, since spam is "relatively" easy to detect, but detecting fraudulent reviews or behaviours is far, far more complicated. A better example would be eBay, Etsy and Amazon. And they clearly fight a very hard battle to fend scammers and spammers, where, as far as I know, they are more or less tied.