code: def get_default_recipients(self):
          ''' Overrides EmailRecipientMixin '''
          return [x.registration.customer.email for x in self.eventregistration_set.filter(cancelled=False)f get_default_recipients(self):
          ''' Overrides EmailRecipientMixin '''
          return [x.registration.customer.email for x in self.eventregistration_set.filter(cancelled=False)]
docs: Overrides EmailRecipientMixin