Responsive: Fluid content alignment http://blog.newzapp.co.uk/2014/10/essential-responsive-email-code-fluid.html
A crash course in the essentials of email design, coding and data http://www.exacttarget.com/products/email-marketing/email-design-toolkit
Six Great Responsive Email Designs http://blog.lyris.com/email-inspiration-six-great-responsive-email-designs/