Hey Ed.
The Email submit is set and cannot be edited by the user. They can only send or cancel.
Two options.
1. You can allow the Send To: command from the file menu but this just emails the current view.
2. Add the fields in your form itself, or create another view where they can update the fields before the email and then have the submit use those fields.
If you would like to see a demo of our workflow setup, which allows this in a task pane, I would be happy to show you.