Email html font size in Outlook

Question

<div style="font-family: Arial; font-size: 10px;">TEST</div>

I'm providing the above source as an html email to Outlook 2007, and it's rendering 7.5px font. Any ideas of what hack I need to make this work?

Edit: I'm setting the mail contents with body, like:

new MailMessage
{
    IsBodyHtml = true,
    Body = "<div style=\"font-family: Arial; font-size: 10px;\">TEST</div>"
};

I don't believe this is related though. Note that if I view source in the generated email the html is as expected. The problem seems to be only that outlook doesn't render it correctly for whatever reason.

Solution

The issue is that most email programs understand very little, if any, CSS. Try specifying the font details using the old, non-CSS methods. This method is deprecated, but unfortunately it is what we have to do to style the emails. It also prevents exact sizing of fonts.

new MailMessage
{
    IsBodyHtml = true,
    Body = "<font face=\"Arial\" size=\"1\">TEST</font>"
};