Ben AJAX ile bir PHP Posta formu kullanıyorum ve herhangi bir mail gönderme değil. Ben burada ne eksik?

send.php

<?php
    error_reporting(E_NOTICE);

    function valid_email($str)
    {
    	return ( ! preg_match("/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*@([a-z0-9\-]+\.)+[a-z]{2,6}$/ix", $str)) ? FALSE : TRUE;
    }

    if($_POST['first_name']!='' && $_POST['last_name']!='' && $_POST['e_mail']!='' && valid_email($_POST['e_mail'])==TRUE && strlen($_POST['message'])>30)
    {
    	$to = 'zacharyrs@gmail.com';
    	$headers = 	'From: '.$_POST['e_mail'].''. "\r\n" .
    			'Reply-To: '.$_POST['e_mail'].'' . "\r\n" .
    			'X-Mailer: PHP/' . phpversion();
    	$subject = "Hello! I'm testing my new ajax email that I got from roscripts.com";
    	$message = htmlspecialchars($_POST['message']);

    	if(mail($to, $subject, $message, $headers))
    	{//we show the good guy only in one case and the bad one for the rest.
    		echo 'Thank you '.$_POST['first_name'].'. Your message was sent';
    	}
    	else {
    		echo "Message not sent. Please make sure you're not
    			running this on localhost and also that you 
    			are allowed to run mail() function from your webserver";
    	}
    }
    else {
    	echo 'Please make sure you filled all the required fields, 
    	that you entered a valid email and also that your message 
    	contains more then 30 characters.';
    }
?>