Creating HTML email is pretty easy, however updating the look and making sure appearance is same across all email clients can be difficult at times. This is because designers write inline CSS to overcome problem of how external CSS is referenced differently in different email clients.
Inline Styler is an online tool that allows that converts your HTML with external CSS into HTML with styles inline. This allows you to develop your CSS HTML email as you would with any other XHTML compliant webpage, using external CSS and without resorting to inline styles, allowing change with a minimum of fuss.
You can also use Inline Styler from your own applications; A simple API is available for Inline Styler for this purpose. By POSTing requests to Inline Styler you can receive a plain-text response containing your converted HTML. Additionally inline <style> tags are also allowed in your code and will be factored into the code output. CSS 2.1 selectors are supported, but some pseudo-classes are not (warnings are given where unsupported rules are used).
Visit Inline Styler: http://inlinestyler.torchboxapps.com/