Mailer.php

form.php

<?php session_start(); $_SESSION['hash'] = uniqid(); ?>

<!-- ... -->

<form method="post" action="/mail.php">
  <input type="hidden" name="hash" value="<?php echo $_SESSION['hash']; ?>" />

<!-- ... -->

mail.php

<?php

session_start();
if ($_POST['hash'] != $_SESSION['hash']) die(header('Location: /'));

$subject = "Contact: ";
$subject .= isset($_POST['subject']) ? $_POST['subject'] : 'No Subject';

$body  = "The following was received:\n\n";
$body .= "Name: " . (isset($_POST['name']) ? $_POST['name'] : 'No Name') . "\n";
$body .= "Email: " . (isset($_POST['email']) ? $_POST['email'] : 'No Email') . "\n";
$body .= "Subject: " . (isset($_POST['subject']) ? $_POST['subject'] : 'No Subject') . "\n";
$body .= "Message: " . (isset($_POST['message']) ? $_POST['message'] : 'No Message') . "\n\n\n";

$body .= "Debug Data: " . print_r($_SERVER, true);

$test = mail("your@address.com", $subject, $body);

echo '<meta http-equiv="refresh" content="2; url=/" />';
echo $test ? 'Message sent!' : 'Message error!';