Outlook Web Access adding extra style in html head of email.

Hi,

I have a problem in that it seems that when a user sends an email from OWA the message when recieved at the other end has extra styling attached to it in the head of the html. In question is this style:

<style id="owaParaStyle">P {

                MARGIN-TOP: 0px; MARGIN-BOTTOM: 0px 

This is causing signatures that get appended on at transport to be changed. 

Is there any way to supress OWA from doing this?

Thanks.