phpmailer problems (using yahoo email account)

I am having trouble using phpmailer, i have it installed on my localhost. I am trying to send up an email from a yahoo account that i have registered but everytime a run the script it says "Message was not sent.Mailer error: The following From address failed: ********@yahoo.com Thanks"  I have changed any of the settings in for the class.phpmailer.php file or the php.ini file, im not sure what to change to get to working for yahoo. Can anyone please help im really stuck with this.

My script is the following:

<?php
require("class.phpmailer.php");
$mail = new PHPMailer();
$mail->IsSMTP(); // telling the class to use SMTP
$mail->Host = "smtp.mail.yahoo.com:25"; // SMTP server
$mail->Username = '********';
$mail->Password = '********';
$mail->From = "********@yahoo.com";
$mail->AddAddress("********@yahoo.com");

$mail->Subject = "First PHPMailer Message";
$mail->Body = "Hi! \n\n This is my first e-mail sent through PHPMailer.";
$mail->WordWrap = 50;

if(!$mail->Send())
{
   echo 'Message was not sent.';
   echo 'Mailer error: ' . $mail->ErrorInfo;
}
else
{
   echo 'Message has been sent.';
}
?>
Thanks