Mail sent fail via smtp

[suzie]

Dear, In our Website we have an option to send an e-mail..where I'amusingthe send_email function to send via SMTP.the function was workingcorrectly and e-mails were sent, but todaywhen trying to send an e-mail,it gives me: 'error: send e-mail failed.SMTP is up and running. (were-start it and we re-start the IIS serverbut nothing change)please Ineed help to know why mail are not sent.(here is the function)thank you,Sincerely,

Test script:

function send_email($to, $subject, $message, $from, $name)

{ require("includes/class.phpmailer.php");

$mail = newPHPMailer();

$mail->IsSMTP(); // send via SMTP

$mail->Host = "localhost"; // SMTP servers

$mail->SMTPAuth =false; // turn on SMTP authentication

$mail->From = $from;

$mail->FromName = $name;

$mail->AddAddress($to);// optional name

$mail->AddReplyTo($to,"");

$mail->WordWrap = 50; // set word wrap

$mail->IsHTML(true); // send as HTML

$mail->Subject = $subject;

$mail->Body = $message;

$mail->AltBody = $message;

if(!$mail->Send())

{ print"<script>
alert('error: send e-mail failed');

window.close()

</script>";

echo "Mailer Error: " . $mail->ErrorInfo;

} else

{ print"<script>

      alert('e-mail sent successfully');                

window.close()

</script>";

}

}