I would set up the email connection to use a form field for the "to" and the "subject". Then you can either put those fields on the form for your user, or have some other fields the user can fill out to append to the original "to" address or subject... Or you could let the user enter Cc's or something like that. Simple sample attached. Save the sample locally, right click and select Design to open in design mode. From there you can look at the data connection, preview, etc.