Php

Hello,

I have this form.php code

<?php
if(isset($_POST['submit'])) {

$to = "davidraiben3@gmail.com";
$emailSubject = 'contactform';

$name = $_POST['name'];
$email_form = $_POST['email'];
$phone = $_POST['phone'];

// validation expected data exists
if(!isset($_POST['name']) ||
!isset($_POST['email']) ||
!isset($_POST['phone'])
) {
echo "&#1497;&#1513;&#1504;&#1492; &#1489;&#1506;&#1497;&#1492; &#1489;&#1496;&#1493;&#1508;&#1505; &#1513;&#1502;&#1497;&#1500;&#1488;&#1514;";
}

$error_message = "";
$email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}$/';
if(!preg_match($email_exp,$email_form)) {
$error_message .= '&#1492;&#1488;&#1497;-&#1502;&#1497;&#1497;&#1500; &#1513;&#1492;&#1494;&#1504;&#1514; &#1500;&#1488; &#1514;&#1511;&#1497;&#1503;.<br />';
}
$email_message = "&#1492;&#1508;&#1512;&#1496;&#1497;&#1501; &#1513;&#1500; &#1513;&#1493;&#1500;&#1495; &#1492;&#1496;&#1493;&#1508;&#1505;.\
\
";

function clean_string($string) {
$bad = array("content-type","bcc:","to:","cc:","href");
return str_replace($bad,"",$string);
}

$email_message .= "&#1513;&#1501;: ".clean_string($name)."\
";
$email_message .= "&#1488;&#1497;-&#1502;&#1497;&#1497;&#1500;: ".clean_string($email_form)."\
";
$email_message .= "&#1496;&#1500;&#1508;&#1493;&#1503;: ".clean_string($phone)."\
";

if (preg_match("/http/i", "$name")) {echo "$CheckMessage"; exit();}
if (preg_match("/http/i", "$email_form")) {echo "CheckMessage"; exit();}
if (preg_match("/http/i", "$phone")) {echo "$CheckMessage";exit();}
$CheckMessage = "URL permitted";

$headers = 'From: '.$email_form."\\r\
";
'Reply-To: '.$email_form."\\r\
" .
'X-Mailer: PHP/' . phpversion();

mail($to,$email_form,$email_message,$headers);
}
/* Results rendered as HTML */
$theResults = <<<EOD
<html lang="he-IL">
<head><meta charset="utf-8">
<title>index.htm</title>:)
<meta http-equiv="refresh" content="10;URL=http://honmashkanta.com/">
<style type="text/css">
<!--
body {
background-color: #444; /* You can edit this CSS to match your website*/
font-family: Verdana, Arial, Helvetica, sans-serif;
font-size: 20px;
font-style: normal;
line-height: normal;
font-weight: normal;
color: #fec001;
text-decoration: none;
padding-top: 200px;
margin-left: 150px;
width: 800px;
}
-->
</style>
</head>
<body>
<div>
<div align="center">&#1508;&#1512;&#1496;&#1497;&#1497;&#1498; &#1504;&#1511;&#1500;&#1496;&#1493; &#1489;&#1492;&#1510;&#1500;&#1495;&#1492;, &#1504;&#1497;&#1510;&#1493;&#1512; &#1511;&#1513;&#1512; &#1489;&#1492;&#1511;&#1491;&#1501;</div>
</div>
</body>
</html>
EOD;
echo $theResults;

?>

when I try to send it it says:
Warning: mail() [function.mail]: SMTP server response: 503 This mail server requires authentication when attempting to send to a non-local e-mail address. Please check your mail client settings or contact your administrator to verify that the domain or address is defined for this server. in C:\Inetpub\vhosts\honmashkanta.com\httpdocs\form.php on line 44
פרטייך נקלטו בהצלחה, ניצור קשר בהקדם
what seems to be the problem the code has worked before

You should be sending the email from your sites email address and the reply to would be the from email.

$headers = 'From: '.$site_email."\\r\
" .
'Reply-To: '.$email_form."\\r\
" .
'X-Mailer: PHP/' . phpversion();