title: Distinguish between first submission of google form and remaining submissions where user is just updating
body: <p>Is it possible to somehow distinguish between the first submission of google form and remaining submissions of same form where user is just updating his previous response? </p>
  
  <p>I have used onSubmit trigger where email notifications are sent every time user submits a form. The problem is that the same email is triggered when the same user updates his form (i.e. when he's made a mistake). I would like to either stop these emails to being sent on update or change the email message?</p>
  
  <p>Can you please suggest if it is possible to achieve this? I think onChange(e) might work.   </p>