A security update for Outlook (2003, 2007, and 2010) was released today and its important that users install this update as the exploit does not require user interaction – just viewing the specially formatted message will kick it off.
RTF message format is affected by this bug. While you can’t filter out RTF formatted messages, if you are really concerned, you can set Outlook to read all messages in plain text.
Microsoft Security Bulletin MS10-087 – Critical
http://www.microsoft.com/technet/security/bulletin/ms10-087.mspx