Campaign Monitor provides and online in-liner for converting style sheets to inline css. But see also:
- Responsive Email Patterns
- Mailchimp css reset styles
- Email on Acid’s Boilerplate for HTML Emails
- Foundations: Email Coding 101
- Jason Rodriguez’s Modern HTML Email Print and ebook editions. Sample available with your email address.
- The Ultimate Guide to CSS – CSS support for every popular mobile, web and desktop email client on the planet
Dealing with Outlook
- Coding Responsive Emails That Work
- Outlook: Your Best Worst Enemy for Responsive Emails – pub 10/14/13
- Responsive Email Templates in Outlook: Tips and Pitfalls
Interesting hack from campaign monitor: How to set the order of stacked columns in a responsive email design, using a column table and the the dir attribute.