xhtml - php simple contact form not sending mail even after confirmation

I have been trying to get a php contact form working on my portfolio site (currently on a free megabyet.net account), but on testing it(on the uploaded site) even though i get the thankyou/confirmation message, I still don't receive any message on my mail account (specified in the code), I can't seem to understand the problem here....help needed!

can it be something related to SMTP??

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Here's the code :

if(isset($_POST['submit'])) {


$to = "vishu_unlocker@yahoo.com";
$subject = "Portfolio Contact";
$name_field = $_POST['name'];
$email_field = $_POST['email'];
$message = $_POST['message'];
$headers = "From: $email_field";
$body = "From: $name_field\n E-Mail: $email_field\n Message:\n $message";

echo "Mail has been sent, thankyou!";
mail($to, $subject, $body, $headers);


} else {

echo "blarg!";

}
?>

HTML Code:

Name :


E-Mail Address :


Message :

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