PHPMailer 报错 Could not instantiate mail function.

<?php/*** Simple example script using PHPMailer with exceptions enabled* @package phpmailer* @version $Id$*/require '../class.phpmailer.php';try {	$mail = new PHPMailer(true); //New instance, with exceptions enabled	$body             = file_get_contents('contents.html');	$body             = preg_replace('/\\\\/','', $body); //Strip backslashes	$mail->IsSMTP();                           // tell the class to use SMTP	$mail->SMTPAuth   = true;                  // enable SMTP authentication	$mail->Port       = 25;                    // set the SMTP server port	$mail->Host       = "smtp.163.com"; // SMTP server	$mail->Username   = "****@163.com";     // SMTP server username	$mail->Password   = "***";            // SMTP server password	//$mail->IsSendmail();  // tell the class to use Sendmail	$mail->AddReplyTo("***@163.com","First Last");	$mail->From       = "***@163.com";	$mail->FromName   = "phpmailer";	$to = "***@qq.com";	$mail->AddAddress($to);	$mail->Subject  = "First PHPMailer Message";	$mail->AltBody    = "To view the message, please use an HTML compatible email viewer!"; // optional, comment out and test	$mail->WordWrap   = 80; // set word wrap	$mail->MsgHTML($body);	$mail->IsHTML(true); // send as HTML	$mail->Send();	echo 'Message has been sent.';} catch (phpmailerException $e) {	echo $e->errorMessage();}?>