PHPMailer 出错 Could not instantiate mail function

PHPMailer 报错 Could not instantiate mail function.
我在phpmailer官网下载的最新的库，根据里面自带的test下的测试文件配置的，php.ini里面也支持sockets。上网查了许多资料也都试了还是不行，故在此请教各位大神指点指点，不胜感激！！！

<?php<br />/**<br />* Simple example script using PHPMailer with exceptions enabled<br />* @package phpmailer<br />* @version $Id$<br />*/<br /><br />require '../class.phpmailer.php';<br /><br />try {<br />	$mail = new PHPMailer(true); //New instance, with exceptions enabled<br /><br />	$body             = file_get_contents('contents.html');<br />	$body             = preg_replace('/\\\\/','', $body); //Strip backslashes<br /><br />	$mail->IsSMTP();                           // tell the class to use SMTP<br />	$mail->SMTPAuth   = true;                  // enable SMTP authentication<br />	$mail->Port       = 25;                    // set the SMTP server port<br />	$mail->Host       = "smtp.163.com"; // SMTP server<br />	$mail->Username   = "[email&#160;protected]";     // SMTP server username<br />	$mail->Password   = "***";            // SMTP server password<br /><br />	//$mail->IsSendmail();  // tell the class to use Sendmail<br /><br />	$mail->AddReplyTo("[email&#160;protected]","First Last");<br /><br />	$mail->From       = "[email&#160;protected]";<br />	$mail->FromName   = "phpmailer";<br /><br />	$to = "[email&#160;protected]";<br /><br />	$mail->AddAddress($to);<br /><br />	$mail->Subject  = "First PHPMailer Message";<br /><br />	$mail->AltBody    = "To view the message, please use an HTML compatible email viewer!"; // optional, comment out and test<br />	$mail->WordWrap   = 80; // set word wrap<br /><br />	$mail->MsgHTML($body);<br /><br />	$mail->IsHTML(true); // send as HTML<br /><br />	$mail->Send();<br />	echo 'Message has been sent.';<br />} catch (phpmailerException $e) {<br />	echo $e->errorMessage();<br />}<br />?>

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给出你的下载地址

可能是要求的 php 版本太高了吧？
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//$mail->IsSendmail();
这个去掉的话默认是使用系统的mail函数发送邮件的。会不会是这个原因。