Between promoted tweets, unduly specific banner ads and a never-ending onslaught of marketing emails, it's impossible to escape targeted advertising. Luckily, though, the white noise of the internet can largely be ignored or hidden by ad blockers and spam filters. But what if paper and ink letters started falling through your door, encouraging you to buy that novelty mug you showed an interest in the other day? Well, that nightmare scenario is already a reality, and could become much more prevalent if a trial between Royal Mail and an online retailer proves fruitful (as far as they are concerned, anyway). The UK postal service and an unspecified retailer are currently experimenting with targeted advertising, delivered by snail mail, based on consumers' online activity.