Contact form processing code

<?php

// Include required functions.
require_once ("php/_functions/send_mail.php");

// Prepare necessary variables for later use.
$Page = "_contact_form";

// Check if page was submitted, and within time.
if (Check_Submit ($Template->BUTTON_SUBMIT, 600)) {
    // Was, prepare necessary variables for later use.
    $Message = array ();

    // Validate input variables.
    $Name = Validate ('name', 'name', 'NAME', 'FORM_NAME', $Message, 60, "æøåÆØÅöÖäÄéá");
    $Email = Validate ('email', 'email', 'EMAIL', 'FORM_EMAIL', $Message);
    $Comments = Validate ('string', 'message', 'MESSAGE', 'FORM_MESSAGE', $Message, "+", "\r\n.?!:;,/'\"%@æøåÆØÅöÖäÄ_£€$");

    // Check to see if everything validated correctly.
    if (!empty ($Message)) {
        // Didn't, prepare the error message for display, and stop processing.
        $Message = "<ul>\n\t<li>".implode ("</li>\n\t<li>", $Message)."</li>\n</ul>\n";
        $Template->_MESSAGE = '<p id="form_error" class="message error">'.sprintf ($Template->ERROR_FORM, $Message)."</p>\n";
        return;
    }

    // Send mail to site owner.
    Send_Mail ($Name, $Email, $Template->MAIL_CONTACT_SUBJECT, $Comments);

    // Succeeded, send to "OK" page and prevent F5-resend.
    header ("Location: {$Template->_PHP_SELF}send=ok");
    die ();
}

// Check if form was submitted at all.
if (Check_Submit ($Template->BUTTON_SUBMIT)) {
    // Wasn't submitted within time limit, show warning and populate fields with submitted data.
    $Template->_FORM_FIELD_NAME = htmlspecialchars ($_POST['name']);
    $Template->_FORM_FIELD_EMAIL = htmlspecialchars ($_POST['email']);
    $Template->_FORM_FIELD_MESSAGE = htmlspecialchars ($_POST['message']);
    $Template->_MESSAGE = '<p id="form_error" class="message error">'.$Template->ERROR_TIME_EXPIRED."</p>\n";
    unset ($_GET['send']);
}

// Check if submission was completed successfully.
if ($_GET['send'] == "ok") {
    // Mail was sent successfully, and it's time to display the "OK" message.
    $Template->_MESSAGE = '<p id="form_error" class="message green">'.$Template->MAIL_SUBMITTED."</p>\n";
}