<html>
  <head>
    <title> Hier ein Glücklicher Kunde </title>
  </head>
<body>
    <form action="" method="post">
        <label for="message" > Deine Nachricht: </label>
        <input id="message" name="message" maxlength="100">
        <br>
        <br>
        <label for="email" > An folgende E-Mail Adresse: </label>
          <input id="email" name="email" maxlength="100" type="email"  >
          <br>
          <br>

          <label for="subject"> Betreff: </label>
          <input id="subject" name ="subject" maxlength="100" >
        <br>
        <br>
        <br>
        <button type="submit" name="sub" value="call">Send</button>
    </form>
</body>
</html>

<?php
if (isset ($_POST['sub'] ))
{
    $to = $_POST ['email'];
    $subject = $_POST ['subject'];
    $message = $_POST['message'];
    $headers = 'From: [email protected]' . "\r\n" .
                'Reply-To: [email protected]' . "\r\n" .
                'X-Mailer: PHP/7.2' . phpversion();
    mail($to, $subject, $message, $headers);
}
?>