Valid Code in HTML/CSS Emails

CSS support in email clients is all over the map. Some have great support, some have almost no support, and most fall somewhere in between. Figuring out what to use and what to leave out is tricky at best, especially if you constantly have to refer back to charts and graphs that tell you what does and does not work in each client.

Fractal is a tool developed by Campaign Monitor that validates your HTML and CSS and lets you know which clients your email will and won’t work in. Fractal gets even more useful, though: in addition to flagging the parts of your code that are unlikely to work, it also gives you suggestions on how to fix the problems. You can even contribute your own fixes to make the app even better.