I'm really struggling to understand what you want to do, sorry its probably my fault. Is each user emailing back? In which case depends if they got the box ticked to automatically add a signature, if not then the email is sent without one. I select mine manually depending who I'm sending the email to.
I'm not sure if this is any use?:
<p align="left"><font color="#000000">subject=Weekly Reports&body=Please find your report attached.</font>
<a href="mailto:[email protected]">click here</a></p>