The Email Standards Project is about working with email client developers and the design community to improve web standards support and accessibility in email. The project was formed out of frustration with the inconsistent rendering of HTML emails in major email clients.

Their mission is to drive the use and support of web standards in email, working with email client developers to ensure that emails render consistently. This is a community effort to improve the email experience for designers and readers, and they’d love your help.

They would like to help web designers understand why web standards matter for email, so that they are willing to get involved in making it happen. And also, they are providing as much assistance and feedback to the email client developers as they can. You can see the beginnings of this with their email acid test results.

Source: http://www.email-standards.org/