PHPMailer在Windows上引发隐秘异常

Question

I have the following code snippet in my php script:

$mail = new PHPMailer(true);               
$mail->SMTPDebug = 1;
$mail->SMTPAuth = true;
$mail->SMTPSecure = "tls";
$mail->Host = "smtp.gmail.com";
$mail->Port = 587;
$mail->UserName = '[e-mail]';
$mail->Password = 'XXX';
$mail->Subject = 'TEST';        
$mail->MsgHTML($msg);       
$mail->AddAddress('[e-mail]','Test User');
$mail->SetFrom("[e-mail]","My User");
if(!$mail->Send()){
    echo "Mailer Error: " . $mail->ErrorInfo;
}else{
    echo "Message has been sent";
}    

The $mail->Send() method never finishes executing so no error is returned but debugging with php I get the following in my browser debugging console:

<b>Fatal error</b>:  Uncaught exception 'phpmailerException' with message 'Could not instantiate mail function.' in ...\data\phpmailer\class.phpmailer.php:779
Stack trace:
#0 ...\data\phpmailer\class.phpmailer.php(662): PHPMailer-&gt;MailSend('Date: Fri, 4 Ap...', '--b1_50a0740efb...')
#1 ...\data\phpmailer\class.phpmailer.php(588): PHPMailer-&gt;PostSend()
#2 ...\data\utils.php(255): PHPMailer-&gt;Send()
#3 ...\data\utils.php(164): emailUploadNotification('ce219bf6-7188-1...', Array, 'ce219bf6-7188-1...')
#4 {main}
  thrown in <b>...\data\phpmailer\class.phpmailer.php</b> on line <b>779</b><br />

I need some help finding out why I cannot send emails from my php script. Thank you.