Use GEOIP in Wordpress to protect contact form.

functions.php

//GeoIP gebruiken om contact pagina te beschermen tegen spammers

// Dynamisch pad bepalen voor Composer autoload
$autoload_path = ABSPATH . 'vendor/autoload.php';

if (!file_exists($autoload_path)) {
    error_log('Composer autoload.php niet gevonden. Controleer of Composer correct is geïnstalleerd.');
    return; // Stop het script als Composer niet beschikbaar is
}

require_once $autoload_path;

use GeoIp2\Database\Reader as GeoIpReader;

function restrict_access_with_php_redirect() {
    $user_ip = $_SERVER['REMOTE_ADDR'];
    $reader = new GeoIpReader('/usr/share/geoip/GeoLite2-Country.mmdb');

    try {
        // Haal landcode en -naam op voor de bezoeker
        $record = $reader->country($user_ip);
        $country_code = $record->country->isoCode;
        $country_name = $record->country->name;

        // Log de landcode voor debuggen
        error_log("Landcode: " . $country_code);

        // Controleer toegang op basis van pagina
        if (is_page('contact')) {
            $allowed_countries = ['NL', 'BE']; // Toegestane landen voor /contact
            if (!in_array($country_code, $allowed_countries)) {
                show_overlay_and_redirect("Access to this page is not allowed from $country_name.");
            }
        } elseif (is_page('contact-us')) {
            $allowed_countries = ['US', 'GB', 'CA', 'AU', 'NL', 'BE']; // Toegestane landen voor /contact-us
            if (!in_array($country_code, $allowed_countries)) {
                show_overlay_and_redirect("Access to this page is not allowed from $country_name.");
            }
        }
    } catch (Exception $e) {
        error_log("GeoIP-locatiefout: " . $e->getMessage());
        wp_die('Er is een probleem opgetreden bij het controleren van je locatie.');
    }
}

// Functie om overlay en redirect te genereren met PHP
function show_overlay_and_redirect($message) {
    // HTML en CSS voor de overlay
    echo "
        <style>
            #access-denied-overlay {
                position: fixed;
                top: 20%;
                left: 50%;
                transform: translate(-50%, -20%);
                width: 300px;
                background-color: rgba(0, 0, 0, 0.9);
                color: white;
                z-index: 9999;
                display: flex;
                flex-direction: column;
                align-items: center;
                justify-content: center;
                font-size: 14px;
                text-align: center;
                border-radius: 8px;
                padding: 20px;
                box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
                opacity: 0.95;
            }
            #access-denied-overlay p {
                margin: 10px 0;
            }
        </style>
        <div id='access-denied-overlay'>
            <p>$message</p>
            <p>You will be redirected to the homepage in 6 seconds.</p>
        </div>
    ";

    // Header-redirect na 6 seconden
    header("Refresh:6; url=" . home_url());
}

add_action('template_redirect', 'restrict_access_with_php_redirect');

requires geoip database installed "/usr/share/geoip/GeoLite2-Country.mmdb"
run "composer require geoip2/geoip2" from the home directory of your project