linux上用ci框架发邮件失效

Question

在window上可以的，linux上发邮件就失效？是linux哪里还需要配置吗?

代码应该没问题

  $this->load->library('email');            //加载CI的email类
            $smtp= $this->config->item("smtp");
            $config['protocol'] = 'smtp';
            $config['smtp_host'] = 'smtp.163.com';
            $config['smtp_user'] = $smtp['user'];
            $config['smtp_pass'] = $smtp['password'];
            $config['mailtype'] = 'html';
            $config['validate'] = true;
            $config['priority'] = 1;
            $config['newline'] = "\r\n"; //linux 为\r 
            $config['smtp_port'] = 25;
            $config['charset'] = 'utf-8';
            $config['wordwrap'] = TRUE;
            $this->email->initialize($config);

            //以下设置Email内容
            $this->email->from('[e-mail]', 'mike');
            $this->email->to($smtp['receiver']);
            $this->email->subject("sss");
            $this->email->message("qq");

            $result = $this->email->send();