Adding CC to custom 'Submit' button

With much help from here in the past (thank you!), we've been using a form with a custom submit button, and I'm needing to add a cc.  I did add a var vCC = first.last@email.com, but no luck in placing it within this event properly.  What is the right way to add an additional cc?  Thank you!

 
event.target.submitForm({cURL:"mailto: "+ vEmail +"?subject=" + vSubject +"&body=" + vBody,cSubmitAs:"PDF",cCharset:"utf-8"});obj.close();