Outlook Web App incorrectly renders HTML emails that don't reside in the Inbox

Working on an HTML email, we've gotten the email to render properly everywhere: Outlook 2010, Mozilla Thunderbird, Horde/IMP, Gmail, Yahoo, etc. etc. However, when the email is checked via the Outlook Web App (Exchange 2010), the HTML email is incorrectly rendered sometimes.

The two issues we're seeing is that in Internet Explorer and Firefox, the font-size CSS in-line directives aren't respected and in Firefox, a gap is put between the table cells, breaking the image. This only happens when the message is NOT in the Inbox. If we drag the message from a folder into the Inbox, the problems disappear. Drag it back into a folder and they reappear. If we open the message in a new window (instead of in the preview pane), the message renders properly.

I'm guessing the CSS of the Outlook Web App is interfering, but I'm hoping someone has had a similar issue and might be able to shed some light on how we can fix this problem.

Here is the relevant message source as seen in the client:

<html>
  <head>
    <style>a{color:#BF0005}</style>
  </head>
  <body bgcolor="#F5F5F5" style="margin:0;text-align:center">
  <table cellpadding="0" cellspacing="0" style="width:604px;margin:0 auto;font-family:Tahoma,sans-serif;font-size:10pt;line-height:16pt">
    <tr>
      <td rowspan="3" style="vertical-align:top;width:10px"><img src="cid:2e39cc62f2ab417d1b9461b437c72ffc" width="10px" height="410px" /></td>
      <td style="padding-top:10px;margin-bottom:0;vertical-align:bottom;width:584px;height:84px"><img style="vertical-align:bottom" src="cid:5ed2b7dfeca322e0d1e0b40bd3a0a48d" width="584px" height="84px" alt="Image Alternate Text Here" /></td>
      <td rowspan="3" style="vertical-align:top;width:10px"><img src="cid:6f108f42f85401cababf9d5dc64fb8f9" width="10px" height="410px" /></td>
    </tr>
    <tr>
      <td style="vertical-align:top;text-align:left;background-color:#FFF;padding:0 50px 40px">
        <h1 style="text-align:center;margin-top:15px;font-size:12pt">Header</h1>
        <p>This is a test email.</p>
      </td>
    </tr>
    <tr>
      <td colspan="3" style="padding:30px 50px;font-size:8pt;text-align:center;color:#888888;line-height:10pt">Footer text</td>
    </tr>
  </table>
  </body>
</html>

EDIT: I've done some digging into the source via Firebug, and I think I've narrowed it down to being a problem with the Outlook Web App. In the Inbox view, the body of the messages are encapsulated in an <iframe> and the contents of the HTML message are unchanged. However, viewing the source of messages in other folders, no <iframe> is used and the <body> tag of the message is converted into a <div> by OWA. The message is then incorporating styles from the OWA style sheet that seem to be overwriting the inline style of the HTML email.

I think we're going to open up a ticket with Microsoft.

Solution

Unfortunately, this problem is a Microsoft issue. We've opened a ticket with them a while ago, but have not heard back. Therefore, we'll just have to make do.