asp:Hyperlink control - using mailto with html body

I want to open a new email using the default mail client with html formatted text in the body.   I can do it with normal text by setting the NavigateURL as follows:   mailto:user@example.com?subject=TestSubject&body=" & strBody   but strBody is a string with basic formatting. I want to be able to have html formatting so that I can design the layout of the email with a table or something similar. At the very least I want to be able to include tabbing. I've tried using %09 control character, but it gets ...