Nope, believe it or not, ever since Outlook 2007 it uses the HTML rendering engine from Word itself. Seriously! Someone at Microsoft looked at Outlook and said "this needs to have the same rendering capabilities as noted Web browser Microsoft Word." Sheesh.

I think they thought ‘lets just use Word to compose replies, but to prevent the email from getting corrupted once the user hits reply, we’ll already mangle it on the way in so the sender gets the blame’