code: def clean_email(self):
          
          try:
              accounts = APPLICATION.accounts.search({'email': self.cleaned_data['email']})
              if len(accounts):
                  msg = 'User with that email already exists.'
                  raise forms.ValidationError(msg)
          except Error as e:
              raise forms.ValidationError(str(e))
  
          return self.cleaned_data['email']
docs: Check if email exists on Stormpath.
  
          The email address is unique across all Stormpath applications.
          The username is only unique within a Stormpath application.