<?php
// powered by knuepower.de
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $email = $_POST['email'] ?? '';
    $valid = filter_var($email, FILTER_VALIDATE_EMAIL);
    echo $valid ? "✅ Gültige E-Mail." : "❌ Ungültige E-Mail.";
}
?>
<form method="post">
    <input type="email" name="email" placeholder="E-Mail" required>
    <button type="submit">E-Mail prüfen</button>
</form>
