Here are some things I've learned about Outlook 2007 that weren't obvious at first, and that you might want to watch out for.

HTML email rendering changes
Although most people don't realize this, Outlook 2003 used Internet Explorer to display (render) HTML email messages. That arrangement had some problems, including the fact that how an HTML email message was rendered in Outlook depended on which version of Internet Explorer you used. Now Internet Explorer 7 (IE7) is available, and Microsoft is pushing hard to get it installed on everyone's PC. IE7 does a better job of rendering HTML than IE6, and it supports recent standards for how this rendering is done.

So things should be getting better when it comes to rendering HTML email messages in Outlook 2007, right? Not exactly.

While Microsoft has never tried to hide this, until recently, few of us realized that Outlook 2007 does not use Internet Explorer to render HTML anymore. Instead, it uses Word 2007. According to Microsoft (see the Microsoft Office Outlook 2007 email editor white paper listed at the end of this article), this switch is a big improvement for people who read and edit HTML email messages in Outlook. It's meant to provide consistency, and ensure that your messages look the same for every Outlook 2007 user.

Unfortunately, Word isn't nearly as good as Internet Explorer at supporting the current HTML standards. Word 2007 doesn't support dozens of the properties that are in the current Cascading Style Sheet (CSS) standard. These properties control much of how HTML appears on the screen. The result of this is that many HTML messages and newsletters that you have been reading just fine for years with earlier versions of Outlook won't look right in Outlook 2007.

In a quick check of the stuff in my Inbox, I found that only the simplest HTML email messages displayed 100% correctly. The biggest problems seem to be in the positioning of graphics on the screen and in colors.