Even though Microsoft Office 2007 isn't due for release for several months (late 2006 to volume license customers; early 2007 for retail and OEM customers), Microsoft is already documenting key changes to the product to help with the transition. The latest effort is a detailed description of which HTML elements and Cascading Style Sheets (CSS) features Outlook 2007 will support in email messages. The two-part MSDN article "Word 2007 HTML and CSS Rendering Capabilities in Outlook 2007" (see the URLs below) is must reading for any organization that sends newsletters or other standard or automated messages in HTML format. It tells you what you need to know to ensure that the messages look good in Outlook 2007, which has better CSS support than any earlier version.
In addition, Microsoft has released a validation tool to check HTML and CSS files in Visual Studio 2005, Office SharePoint Designer 2007, Expression Web Designer 2007, Macromedia Dreamweaver MX 2004, and Dreamweaver 8 for conformance with Outlook 2007's rendering capabilities. Organizations that use any of those applications to generate HTML content to send in messages (e.g., a newsletter) can use this new utility to help determine how that HTML will appear in Outlook 2007. You can download the tool, called Outlook HTML and CSS Validator at http://www.microsoft.com/downloads/details.aspx?familyid=0b764c08-0f86-431e-8bd5-ef0e9ce26a3a&displaylang=en .
What makes this effort both possible and necessary is that Outlook 2007's HTML rendering no longer depends on Microsoft Internet Explorer (IE). In earlier versions, the appearance of an HTML message in Outlook depended in part on which version of IE was installed on the system. Starting with Outlook 2007, the IE dependency goes away. Instead, just as Outlook 2007 uses Office Word 2007 as the sole editor for all types of Outlook items, it also uses Word 2007's rendering engine to display HTML messages. Thus, for the first time, it's possible to determine in advance precisely how Outlook will render an HTML message, regardless of what IE version the system has.
This lack of dependency on IE also shows itself in another way that security-conscious administrators will like. In earlier versions, Outlook had a View, View in Internet Zone command on its toolbar to allow a user to render an HTML message in the less secure Internet zone, for example, when the message contained a script. The \[script\] html tag (replace brackets with angle brackets -- Another blocked HTML tag is \[form\], along with the tags for all form controls. This means that you can't send an Outlook user an HTML message that contains a form with a Submit button to return results either in an email message or to a Web site. The data entry controls and Submit button won't even be visible to the Outlook 2007 user. To submit the form, the user would have to use the View in Browser command to view the HTML content in a browser.
This change definitely is going to affect some businesses. For example, Aliencamel.com, an email provider based in Australia, currently relies on the user interacting with an email-based form to release items from a spam quarantine folder. Aliencamel's Sydney Low says the company is exploring two possible solutions to accommodate Outlook 2007 users--either an add-in that provides a toolbar button to perform the same functionality or a change in its HTML code to add browser/rendering detection so that users see a message optimized for Outlook 2007. Ideally, Low says, "If the email is being displayed in Outlook 2007, it would say 'Click on this link to display the content,' but in other clients, an HTML form would be displayed."
If you want to give the validation tool a whirl, I recommend that you download the free trial version of the new Microsoft Expression Web Designer, a Web page editor designed from the ground up to work with CSS. Once you install Expression, follow the instructions in the "Word 2007 HTML and CSS Rendering Capabilities in Outlook 2007 – Part 2" article to add the ability to check HTML and CSS against the schema for Outlook. Open any HTML file that you want to test, and edit the HTML code to remove any attributes on the \[html\] tag. Then choose Tools, Compatibility Reports. Under "Check HTML/XHTML compatibility with," choose "HTML for Word 2007." Under "Check CSS compatibility with," choose "CSS Word 2007." Clear the box for "Run check based on doctype declaration in page if available." Then, click Check. Expression will display a compatibility report showing all the validation errors. Double-click any line in the report, and you'll go directly to the code with the validation error.
Compare the validation errors with the detailed list of supported and unsupported tags and attributes in the articles, especially Part 1, and you'll see how the rendering restrictions on HTML messages in Outlook 2007 add to Outlook's security. For example, the title attribute, which is used on Web pages to provide screen tips, isn't supported at all. This means the sender can't use a title attribute to hide the destination of a hyperlink; the screen tip for the link will always show the actual URL. Similarly, the \[a\] tag used for links doesn't support the class attribute. That approach prevents the sender from using a style to make some links look different from others. A link to external content in the background property of a style won't work at all (even if Outlook is otherwise configured to download external content for HTML messages).
This new validation tool isn't perfect. Because it depends on the compatibility-checking capability of the underlying HTML editor, it might not show a validation error for every unsupported style feature listed in the articles. For example, it didn't tell me about an external URL that I had included in the background property of my style for the \[body\] tag. But, combined with the detailed documentation in the article on Outlook 2007 rendering capabilities, organizations that want to start designing newsletters and other complex HTML-format messages for Outlook 2007 now can get a solid head start.
Word 2007 HTML and CSS Rendering Capabilities in Outlook 2007 (2 parts) http://msdn2.microsoft.com/en-us/library/aa338201.aspx http://msdn2.microsoft.com/en-us/library/aa338200.aspx
Microsoft Expression Web Designer Community Technology Preview 1 http://www.microsoft.com/products/expression/en/web_designer/wd_free_trial.aspx