CareerBuilder's Scott Burdsall is giving a presentation at the Email Insider Summit on the increasingly attention-grabbing subject of responsive design and mobile. He says there are three ways to consider the mobile experience: "desktop centric," "mobile aware" and "responsive." Very simply, "responsive" optimizes the email such that it fits and looks best on the mobile device on which it is opened. Not every mobile device can be used with responsive design, but the list includes iOS devices, the Kindle, Android 2.2+, a Blackberry version and Windows Phone 7.5. There are five responsive tactics that Burdsall cites: stack, hide, replace, resize and restyle. In one arena, CareerBuilder saw a 21-24% increase in click-through rates with responsive design on mobile and "less motivated users seem more likely" to respond. Burdsall says responsive design can bring "less busy design highlights (in) more critical sections" and for customers "the inherent need to focus."