The following is republished from the Tech Times #156.

If support for web standards in browsers is improving slowly, then support in email clients is moving at a glacial pace. Attempts to document things like CSS support in the major email clients have revealed a depressing state of affairs, but with recent desktop clients like Thunderbird now sitting on solid rendering engines, things have been looking up.

All that changed when Microsoft dropped a lump of coal into every web developer’s stocking with the end-of-year release to business customers, and the upcoming consumer release, of Outlook 2007.

At the risk of turning this newsletter into a biweekly Microsoft bash, Redmond has done it again. While the IE team was soothing the tortured souls of web developers everywhere with the new, more compliant Internet Explorer 7, the Office team pulled a fast one, ripping out the IE-based rendering engine that Outlook has always used for email, and replacing it with … drum roll please … Microsoft Word.

That’s right. Instead of taking advantage of Internet Explorer 7, Outlook 2007 uses the very limited support for HTML and CSS that is built into Word 2007 to display HTML email messages.

Having tested the two public beta versions of Outlook 2007 late last year, I knew there was something screwy going on. Many of the newsletters I subscribed to had become unreadable, and SitePoint’s own publications (including the Tech Times) were looking decidedly unhealthy. I dutifully reported these rendering issues with the feedback mechanisms provided in the beta, and wrote them off as Internet Explorer 7 integration issues that would be resolved in the final release.

But late last month, a thread in the SitePoint Forums caught my eye. Microsoft had published a pair of articles describing the support for HTML and CSS in Outlook 2007, and the news wasn’t good:

Microsoft Office Outlook 2007 uses the HTML parsing and rendering engine from Microsoft Office Word 2007 to display HTML message bodies. The same HTML and cascading style sheets (CSS) support available in Word 2007 is available in Outlook 2007.

The limitations imposed by Word 2007 are described in detail in the article, but here are a few highlights:

no support for background images (HTML or CSS)

no support for forms

no support for Flash, or other plugins

no support for CSS floats

no support for replacing bullets with images in unordered lists

no support for CSS positioning

no support for animated GIFs

In short, unless your HTML emails are very, very simple, you’re going to run into problems with Outlook 2007, and in most cases the only solution to those problems will be to reduce the complexity of your HTML email design to accommodate Outlook’s limited feature set.

With the release of Outlook 2007, Microsoft is effectively adding an entirely new rendering engine to the mix—one that designers producing HTML email will not be able to ignore.

Not only that, but this new rendering engine isn’t any better than that which Outlook previously used—indeed, it’s far worse. With this release, Outlook drops from being one of the best clients for HTML email support to the level of Lotus Notes and Eudora, which, in the words of Campaign Monitor’s David Grenier, "are serial killers making our email design lives hell."

Why on earth would Microsoft do such a thing? Security? Microsoft has been shouting from the rooftops about the new security model in Internet Explorer 7 that prevents the nasty security issues that have plagued Outlook in the past. It seems Microsoft doesn’t buy its own publicity, however, because this move sends the message that Internet Explorer’s security model is not to be trusted.

Where to from here? Well, as a first step, you’ll want to use Microsoft’s handy-dandy tool to tell you which parts of your lean, mean HTML emails need to be replaced with old-fashioned HTML sludge. As a second step, you may want to consider giving your Outlook-based readers an easy way to switch to text-only email.

Bring on PDF email. I’m ready.