Footasylum, the British lifestyle footwear retailer, says it has increased its revenue from e-mail marketing by 28 percent by harvesting its existing customer data. According to the company, a recent test showed that its cost per click had been cut by 75 percent. Looking for ways to direct customers to the specific parts of its wide assortment that interest them personally, the company approached Peak, a data-mining firm based in the U.K. and India. Peak claims that companies that mine their data to personalize their marketing for customers are growing 30 percent faster than those that do not.