Hi Ravi,
Yes i checked too, my bad i didn't look it so closely. I saw another option if you can enhance the email component and redefine the INITIALIZE the method and modify the content of gs_sign_settings by appending your text for both html & plain text signature field. When you will open the email activity atleast the body will have that text (example: Sent from SAP CRM). I dont know if that is ok for your requirement.
Regards,
Shobhit