Microsoft is trying to dampen criticism by explaining its controversial decision to unify the rendering and editing engines in Outlook 2007 and use only the Word 2007 engine, even though there are some HTML and Cascading Style Sheet attributes that the engine does not currently support. The move is a significant change from previous versions of Outlook, which actually used two rendering engines: Internet Explorer's engine was used for reading content, while Word was used for editing content when a user was composing messages. Outlook 2007 now uses the HTML parsing and rendering engine from Word 2007 to display HTML message bodies.
However, there are some HTML and CSS attributes that the Word 2007 rendering engine does not support, and Outlook 2007 now does not use the same standards as Internet Explorer 7. The move has not been well-received by some bloggers, such as SitePoint's Kevin Yank, who said in a recent post that instead of taking advantage of Internet Explorer 7, Outlook 2007 uses the very limited support for HTML and CSS built into Word 2007 to display HTML e-mail messages.