How to view all e-mail messages in plain text format in Outlook 2003 and 2007

Microsoft Office Outlook 2003 and Microsoft Office Outlook 2007 provide a new option named the Read all standard mail in plain text option. This option lets you view all e-mail messages in plain text format. If you are concerned that a virus or some other type of malicious script could execute through HTML or through Microsoft Outlook Rich Text Format (RTF), you can use the Read all standard mail in plain text option to display all standard e-mail messages in plain text format. The Read all standard mail in plain text option is for display purposes only. The original e-mail message is not converted to plain text format.

http://support.microsoft.com/kb/831607