How to send email from PHP on XAMPP?

[manu g]

i am using xampp as a server it has apache mercury and all..even if i rum mercury still i get the error

Warning: mail() [function.mail]: Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in C:\xampp\htdocs \mail.php on line 7

my php.ini file has..
[mail function]
; For Win32 only.
; http://php.net/smtp
SMTP = localhost
; http://php.net/smtp-port
smtp_port = 25

and my php code is

<?php
$to = "someone@example.com";
$subject = "Test mail";
$message = "Hello! This is a simple email message.";
$from = "someonelse@example.com";
$headers = "From: $from";
mail($to,$subject,$message,$headers);
echo "Mail Sent.";
?>

when i run portcheck in xampp it shows smtp port 25 as free
please let me know what is the problem