If the form is already created and you configured the Form Function tab to send an email, CSS Form Builder has already added the Universal Email server behavior to the page.
go to Window -> Server Behaviors to open the server behaviors panel.
Double clic kthe Universal Email server behavior
In the universal Email server behavior, click on the to button to get to the advanced Ro options.
click the plus button and add another Entered Value" enter the code I provided previously in the entered value box.