A few years ago, the owners of a flash sale site, Doggyloot, discovered that there is a correlation between the type of dog and the purchasing behaviour of its owner. To test their theory, Doggyloot decided to start segmenting their existing clients based on the age and size of the dogs that they owned. They asked people to fill in a quick survey, asking them about their dogs’ birthdays and sizes. Based on these insights, Doggyloot built three email lists that began targeting their customers with different messages. What do you think happened? There was a 750% CTR increase.