For years, Microsoft has used Internet Explorer to render HTML-based mail in Outlook. That’s all about to change with Outlook 2007. In an effort to increase security, Outlook 2007 will now be using Microsoft Word for HTML rendering. This change means Outlook users will no longer be vulnerable to the exploits that IE suffers from. On the other hand, if you’re like most web designers, the thought of Word and HTML sends chills down your spine.

While I’m no fan of HTML mail, the occasional use is tolerable. If you have to spice up your mail, HTML and CSS is the best way to go. Since not all email clients support HTML mail, CSS offers the ability to degrade to plain text. Not to mention a CSS-based email is much lighter than one filled with tables and other HTML styles.

As you may have guessed, one of many weaknesses of Word’s rendering engine is CSS. The crippled engine only supports basic CSS styling with little to no support for positioning or other layout properties. By using this rendering engine’s functionality in the most popular email client, Microsoft is effectively crippling CSS email designs for the entire internet. No one is going to send a CSS-based email if only 10% of the recipients will be able to view it.

While I can’t complain about the security benefits of the switch, I can about the rendering engine choice. Sure, Outlook has used Word to render composed email for years, but that doesn’t mean that received mail now has to suffer the same fate. And let’s not forget, Word isn’t exactly top class in security either. Microsoft could have chosen a better alternative and they know it. I just hope people continue to stick with CSS-based mail or fall back to plain text. I’m not looking forward to receiving tables in my email again.