$this->load->model('emailmodel');
$query = $this->emailmodel->get_emails();
$emails = array();
set_time_limit(0);

foreach($query->result() as $u)
{
    $this->notification->send($u->to,$this->config->item('neworder'),'orders/mail/subscription',array(
            'order' => $neworder,'user' => $user
        ));
    break;
}

所以我在每个订阅用户的循环中发送邮件,但它给了我一个错误：

Could not execute mail delivery program '/usr/sbin/sendmail -t -i '

怎么解决这个问题？