Since last October, we’ve been tracking the mobile-friendliness of the promotional emails sent by a group of nearly 160 B2C brands. We saw a big bump in the adoption of mobile-aware and responsive design during the holiday season and this summer we expect serious progress, followed by another jump in adoption as we approach Christmas again. Beyond detailing the adoption rates we’ve observed, this infographic explains the difference between desktop-centric design, mobile-aware design, and responsive design—and the future outlook for each of these. It also includes links to examples of mobile-aware and responsive design from the Email Swipe File.