If you rely on HTML email to contact your customers, you’ve probably heard the news that Outlook 2007’s HTML rendering has been downgraded.  A number of CSS properties that were supported in earlier versions of Outlook are no longer supported.

Microsoft offers a validation tool for Outlook 2007, but if you’re a TopStyle user, chances are you’d like to validate from within TopStyle, so I ‘ve created a “style definition” for this purpose.  To install it, just follow these steps:

1. Close TopStyle
2. Download Outlook 2007.def and copy it to TopStyle’s \CSSDefs subfolder
3. Restart TopStyle, then press Shift+Ctrl+D to change the style definition to “Outlook 2007”
4. Press Shift+F6 to configure TopStyle’s style checker to validate against the Outlook 2007 definition
5. Enable “Show browser tips” on the “Error Levels” section of the style checker’s options if you want TopStyle to warn you when you’re using a CSS property that’s not supported on all HTML elements (for example, MARGIN isn’t supported on SPAN elements).

After doing this, TopStyle’s style checker (F6) will let you know when you use any CSS properties and attributes that aren’t supported by Outlook 2007.  In addition, the style inspector will only show CSS properties and attributes that are supported by Outlook 2007, and any unsupported properties in your style sheet will be shown in red.

Note: This style definition is considered a BETA version and was created based on information found here, which I assume to be correct.  If you find any discrepancies, please let me know and I’ll post an update.