CSS Reference : Learn by example: cssreference.io is a free visual guide to CSS. It features the most popular properties, and explains them with illustrated and anima...
Email Standards Project : The Email Standards Project is about working with email client developers and the design community to improve web standards support and accessibility ...
Guide to CSS support in email clients : Designing an HTML email that renders consistently across the major email clients can be very time consuming. We've put together this guide to save you...
