If you have security concerns about reading HTML-formatted messages, you can have Microsoft Office Outlook 2007 automatically display messages that you open in plain text instead. However, reading messages in plain text does not provide full protection against all e-mail hazards.
On the Tools menu, click Trust Center, and then click E-mail Security.
Under Read as Plain Text, select the Read all standard mail in plain text check box.
To include messages signed with a digital signature, select the Read all digitally signed mail in plain text check box.
Note: If you want to view a plain text message in its original format, click the InfoBar, and choose either Display as HTML or Display as Rich Text.