In the past couple of months, I have run into issues deploying the CRM Forward Rule to Outlook 2007 clients. 

If you are facing this issue, you may wish to try installing the CRM 3.0-Exchange E-Mail Router Update.

While the documentation doesn't actually state that issues related to Outlook 2007 can be solved by installing this update, it has corrected the problem on at least three separate CRM installations that I am aware of.