phpmailer在服务器上不能正常发送邮件的解决办法

$this->smtp_conn = @fsockopen( $host,  // the host of the server
                 $port,  // the port to use
                 $errno,  // error number if any
                 $errstr, // error message if any
                 $tval);  // give up after ? secs

$this->smtp_conn = @stream_socket_client( $host.':'.$port,  // the host of the server
                 $errno,  // error number if any
                 $errstr, // error message if any
                 $tval);  // give up after ? secs