def delete_all(self, user=None):
        """
        Method to soft-delete all notifications of a User (if supplied)

        :param user: Notification recipient.

        :return: Updates QuerySet as soft-deleted.
        """
        qs = self.active()
        if user:
            qs = qs.filter(recipient=user)

        soft_delete = getattr(settings, 'NOTIFY_SOFT_DELETE', True)

        if soft_delete:
            qs.update(deleted=True)
        else:
            qs.delete()
Method to soft-delete all notifications of a User (if supplied)

        :param user: Notification recipient.

        :return: Updates QuerySet as soft-deleted.