title: PHP that processes HTML form returns 503 error
body: <p>on my website I use a Form to let users send inqiries directly trough the website. For this I use this PHP code to process, named "sendform.php":</p>
  
  <pre><code>&lt;?php
      $body = 'Online-Anfrage';
      $body .= '\r\n NAME:';
      $body .= $_POST["input_name"];
      $body .= '\r\n EMAIL:';
      $body .= $_POST["input_email"];
      $body .= '\r\n TELEFON:';
      $body .= $_POST["input_telefon"];
      $body .= '\r\n FAHRZEUG:';
      $body .= $_POST["input_fahrzeug"];
      $body .= '\r\n ERSTZULASSUNG:';
      $body .= $_POST["input_erstzulassung"];
      $body .= '\r\n KILOMETERSTAND:';
      $body .= $_POST["input_kilometerstand"];
      $body .= '\r\n PREISVORSTELLUNG:';
      $body .= $_POST["input_preisvorstellung"];
  
      $to = "my@mail.de";
      $headers = 'From: info@mmymail.de' . "\r\n" .
      'Reply-To: ' . $_POST["input_email"] . "\r\n" .
      'X-Mailer: PHP/' . phpversion();
      $subject = "Online-Anfrage";
      if (mail($to, $subject, $body, $headers)) 
      {
          echo("&lt;p&gt;Wir haben Ihre Anfrage erhalten. Vielen Dank für Ihr vertrauen!    &lt;/p&gt;");  
      } 
      else 
      {
          echo("&lt;p&gt;Interner Serverfehler. Bitte rufen Sie uns für eine Anfrage direkt an:&lt;/p&gt;");
      }
  ?&gt;
  </code></pre>
  
  <p>But when I try to use the action="sendform.php" with my index.html I get a server-error 503. The code of the form I use is this one:</p>
  
  <pre><code>                &lt;form class="form-horizontal" method="post" action="sendform.php"&gt;
                      &lt;fieldset&gt;
  
                      &lt;!-- Form Name --&gt;
                      &lt;legend&gt;Kostenlose und unverbindliche Verkaufsanfrage&lt;/legend&gt;
  
                      &lt;!-- Text input--&gt;
                      &lt;div class="form-group"&gt;
                        &lt;label class="col-md-4 control-label" for="input_name"&gt;Name&lt;/label&gt;  
                        &lt;div class="col-md-6"&gt;
                        &lt;input id="input_name" name="input_name" type="text" placeholder="" class="form-control input-md" required=""&gt;
  
                        &lt;/div&gt;
                      &lt;/div&gt;
  
                      &lt;!-- Text input--&gt;
                      &lt;div class="form-group"&gt;
                        &lt;label class="col-md-4 control-label" for="input_email"&gt;E-Mail Adresse&lt;/label&gt;  
                        &lt;div class="col-md-6"&gt;
                        &lt;input id="input_email" name="input_email" type="text" placeholder="" class="form-control input-md" required=""&gt;
  
                        &lt;/div&gt;
                      &lt;/div&gt;
  
                      &lt;!-- Text input--&gt;
                      &lt;div class="form-group"&gt;
                        &lt;label class="col-md-4 control-label" for="input_telefon"&gt;Telefonnummer&lt;/label&gt;  
                        &lt;div class="col-md-6"&gt;
                        &lt;input id="input_telefon" name="input_telefon" type="text" placeholder="" class="form-control input-md" required=""&gt;
  
                        &lt;/div&gt;
                      &lt;/div&gt;
  
                      &lt;!-- Text input--&gt;
                      &lt;div class="form-group"&gt;
                        &lt;label class="col-md-4 control-label" for="input_fahrzeug"&gt;Fahrzeugmodell&lt;/label&gt;  
                        &lt;div class="col-md-6"&gt;
                        &lt;input id="input_fahrzeug" name="input_fahrzeug" type="text" placeholder="" class="form-control input-md" required=""&gt;
  
                        &lt;/div&gt;
                      &lt;/div&gt;
  
                      &lt;!-- Text input--&gt;
                      &lt;div class="form-group"&gt;
                        &lt;label class="col-md-4 control-label" for="input_erstzulassung"&gt;Erstzulassung&lt;/label&gt;  
                        &lt;div class="col-md-6"&gt;
                        &lt;input id="input_erstzulassung" name="input_erstzulassung" type="text" placeholder="" class="form-control input-md" required=""&gt;
                        &lt;span class="help-block"&gt;Bitte Monat und Jahr angeben.&lt;/span&gt;  
                        &lt;/div&gt;
                      &lt;/div&gt;
  
                      &lt;!-- Appended Input--&gt;
                      &lt;div class="form-group"&gt;
                        &lt;label class="col-md-4 control-label" for="input_kilometerstand"&gt;Kilometerstand&lt;/label&gt;
                        &lt;div class="col-md-6"&gt;
                          &lt;div class="input-group"&gt;
                            &lt;input id="input_kilometerstand" name="input_kilometerstand" class="form-control" placeholder="" type="text" required=""&gt;
                            &lt;span class="input-group-addon"&gt;km&lt;/span&gt;
                          &lt;/div&gt;
  
                        &lt;/div&gt;
                      &lt;/div&gt;
                      &lt;!-- Appended Input--&gt;
                      &lt;div class="form-group"&gt;
                        &lt;label class="col-md-4 control-label" for="input_preisvorstellung"&gt;Preisvorstellung&lt;/label&gt;
                        &lt;div class="col-md-6"&gt;
                          &lt;div class="input-group"&gt;
                            &lt;input id="input_preisvorstellung" name="input_preisvorstellung" class="form-control" placeholder="" type="text" required=""&gt;
                            &lt;span class="input-group-addon"&gt;€&lt;/span&gt;
                          &lt;/div&gt;
  
                        &lt;/div&gt;
                      &lt;/div&gt;
                      &lt;button type="submit" class="btn btn-success col-md-12"&gt;Anfrage absenden!&lt;/button&gt;
  
                      &lt;/fieldset&gt;
                      &lt;/form&gt;
  </code></pre>
  
  <p>I have absolutely no idea how to fix this actually since I cannot find any errors in the namings or so, there must be something else causing this error.</p>
  
  <p>The server log does not say anything like "parse error" or so, what you get when there is something wrong with the variables..</p>
  
  <p>EDIT: I do recieve emails but they are only filled with the static text, the variables do not exist in the mails that i recieve</p>
  
  <p>Could you help me with this? Thank!</p>