"It's about time!" is what most people are saying about Gmail's new responsive email support that is supposed to arrive later this month.
THIS IS JUST ONE PART OF AN OVERALL EFFORT TO EXPAND CSS SUPPORT IN GMAIL AND TO GIVE EMAIL DESIGNERS MORE CONTROL OVER HOW THEIR MESSAGES ARE RENDERED.
– Pierce Vollucci, Product Manager at Google
What are they changing exactly?
From a design perspective, the two major changes is their support of the <style> tag and media queries.
What is not included in this update?
The support of embedded web fonts (including Google fonts), animations and pseudo classes such as :hover will not be included. Don't be too disappointed though. The fact Gmail is finally supporting responsive emails is a huge step forward in the right direction!