Outlook's new rendering engine

Outlook has been Microsoft's primary scheduling and email solution for 10 years now. A number of versions have been released over the years, but the latest Outlook 2007 introduces one of the most significant overhauls in the history of the program. With the release of Outlook 2007, Microsoft changed the rendering engine of the mail program from an Internet Explorer-based one to the engine integrated into Word 2007.

Word 2007's HTML parsing and rendering engine lacks many of the functionalities of the one used by Outlook 2003, and that has made some experts say that Microsoft is halting innovation in email design and taking it years into the past.

Outlook's market share

A recent Radicati Group survey shows that MS Outlook accounts for about 60% all of corporate email clients in use. Subsequently, due to the omnipresence of Microsoft products and the prospect of future upgrades, there are now new unofficial standards for designing HTML mail. Although other mail clients like Thunderbird and Eudora are gaining ground, the overwhelming market share of Outlook means that every newsletter designer has to take into account the new rendering capabilities (and disabilities) of Microsoft's latest email client .

With regard to future use of Outlook, it bears mentioning that the email program is bundled with Microsoft Office 2007 – one of the most popular, if not the most popular, franchises in the world of desktop productivity. So far, the new version of the Office suite has been accepted well, and its user base is growing thanks to some noticeable improvements, including a radical redesign of Word's user interface. Also, given Microsoft's tendency to push new products while gradually terminating support options for old ones, it is safe to plan ahead with Outlook 2007 in mind.

The specifics

To put it simply, the new Outlook is incapable of rendering much of what was previously considered normal elements of HTML mail. Most importantly, it lacks support for background images and HTML forms; only a red X appears where Flash animations should be, and animated GIFs show as static images (presumably only the first frame appears); CSS floats and positioning do not work.

Full support is retained for many basic tags like <P> and <A>; the full list of supported and unsupported tags, attributes, and properties is available at the Microsoft Developer Network.

What to do if you can't rely on brainpower alone to render code in your head, and Outlook 2007 is not available on your system? In order to ensure compatibility, Microsoft has made available a validator tool that helps you see emails as if rendered in the new Outlook. The Outlook 2007 HTML and CSS Validator can be downloaded by clicking here.

What does this mean for email designers?

Love it or hate it, HTML mail is a significant part of the bulk of email sent around the world everyday. Virtually every company has its own email newsletter, and most of these are HTML-based. This is a reality that will not change soon, and Outlook will no doubt have an impact on the way HTML mail is designed.

The consensus is that HTML mail will now become simpler. Table-based layout is back, and the days of bells-and-whistles in corporate email are over. The image to the left shows a current Microsoft newsletter.

But there is a silver lining to all this, for both senders and receivers: a more basic rendering engine means less security hazards for Outlook users, while designers will probably see better acceptance of HTML email in general, now that creating an overly-complex and Flash-laden emails has become impractical.

Copyright © 2008 DevStart, Inc. Permission is required to use the material on this page.