you may be confused about what is displayed to the recipient - the regarding is only visible for you - the recpipient will not see that.
The only thing a recipient would see is the optional tracking token added to the subject line. - This is an optional feature that helps replies to CRM emails to be tracked to the original lead/contact/case/opportunity etc.
This can be disabled, but it's a system wide option. -
Here's more information on how it is used:
http://blogs.msdn.com/crm/archive/2008/01/29/what-s-new-in-microsoft-dynamics-crm-4-0-e-mail-integration.aspx
Scott Sewell, CustomerEffective | http:\\blog.CustomerEffective.com | Twitter:@ScottSewell