Why isn't email sent?

Question

Why isn't this script sending an email? It will redirect after sucessfully completed form to success page, but email is not delivered. I'm using similar code on other site (without javascript and autoload inputs) and there is working correctly. I tried to use static variable $mailto but nothink happend too.

<?php
if (session_id() == "")
{`enter code here`
   session_start();
}
if ($_SERVER['REQUEST_METHOD'] == 'POST')
{
   if (isset($_POST['captcha_code'],$_SESSION['random_txt']) && md5($_POST['captcha_code']) == $_SESSION['random_txt'])
   {
      unset($_POST['captcha_code'],$_SESSION['random_txt']);
   }
   else
   {
      echo '<b>Nesprávene opísaný kód z obrázka!</b><br>';
      echo '<a href="javascript:history.back()">Späť</a>';
      exit;
   }
}
?>
<?php
   function ValidateEmail($email)
   {
      $pattern = '/^([0-9a-z]([-.\w]*[0-9a-z])*@(([0-9a-z])+([-\w]*[0-9a-z])*\.)+[a-z]{2,6})$/i';
      return preg_match($pattern, $email);
   }

   if ($_SERVER['REQUEST_METHOD'] == 'POST')
   {
      $mailto = $_POST["adresat"];
      //$mailto = 'michal.palus1@gmail.com';
      $mailfrom = isset($_POST['email']) ? $_POST['email'] : $mailto;
      $subject = 'Nový Feedback';
      $message = 'Napísali Vám:';
      $success_url = '/success.html';
      $error_url = '/error.html';
      $error = '';
      $eol = "\r\n";
      $boundary = md5(uniqid(time()));

      $header  = 'From: '.$mailfrom.$eol;
      $header .= 'Reply-To: '.$mailfrom.$eol;
      $header .= 'MIME-Version: 1.0'.$eol;
      $header .= 'Content-Type: multipart/mixed; boundary="'.$boundary.'"'.$eol;
      $header .= 'X-Mailer: PHP v'.phpversion().$eol;
      if (!ValidateEmail($mailfrom))
      {
         $error .= "Nesprávna emailová adresa!\n<br>";
      }

      if (!empty($error))
      {
         $errorcode = file_get_contents($error_url);
         $replace = "##error##";
         $errorcode = str_replace($replace, $error, $errorcode);
         echo $errorcode;
         exit;
      }

      $internalfields = array ("submit", "reset", "send", "captcha_code");
      $message .= $eol;
      $message .= "IP Address : ";
      $message .= $_SERVER['REMOTE_ADDR'];
      $message .= $eol;
      foreach ($_POST as $key => $value)
      {
         if (!in_array(strtolower($key), $internalfields))
         {
            if (!is_array($value))
            {
               $message .= ucwords(str_replace("_", " ", $key)) . " : " . $value . $eol;
            }
            else
            {
               $message .= ucwords(str_replace("_", " ", $key)) . " : " . implode(",", $value) . $eol;
            }
         }
      }

      $body  = 'This is a multi-part message in MIME format.'.$eol.$eol;
      $body .= '--'.$boundary.$eol;
      $body .= 'Content-Type: text/plain; charset=UTF-8'.$eol;
      $body .= 'Content-Transfer-Encoding: 8bit'.$eol;
      $body .= $eol.stripslashes($message).$eol;
      if (!empty($_FILES))
      {
          foreach ($_FILES as $key => $value)
          {
             if ($_FILES[$key]['error'] == 0 && $_FILES[$key]['size'] <= $max_filesize)
             {
                $body .= '--'.$boundary.$eol;
                $body .= 'Content-Type: '.$_FILES[$key]['type'].'; name='.$_FILES[$key]['name'].$eol;
                $body .= 'Content-Transfer-Encoding: base64'.$eol;
                $body .= 'Content-Disposition: attachment; filename='.$_FILES[$key]['name'].$eol;
                $body .= $eol.chunk_split(base64_encode(file_get_contents($_FILES[$key]['tmp_name']))).$eol;
             }
         }
      }
      $body .= '--'.$boundary.'--'.$eol;
      if ($mailto != '')
      {
         mail($mailto, $subject, $body, $header);
      }
      $search = array("ä", "Ä", "ö", "Ö", "ü", "Ü", "ß", "!", "§", "$", "%", "&", "/", "\x00", "^", "°", "\x1a", "-", "\"", " ", "\\", "\0", "\x0B", "\t", "\n", "\r", "(", ")", "=", "?", "`", "*", "'", ":", ";", ">", "<", "{", "}", "[", "]", "~", "²", "³", "~", "µ", "@", "|", "<", "+", "#", ".", "´", "+", ",");
      $replace = array("ae", "Ae", "oe", "Oe", "ue", "Ue", "ss");
      foreach($_POST as $name=>$value)
      {
         $name = str_replace($search, $replace, $name);
         $name = strtoupper($name);
         $form_data[$name] = $value;
      }
      header('Location: '.$success_url);
      exit;
   }
?>
<script type="text/javascript" src="jquery-1.8.0.min.js"></script>   
<script type="text/javascript">
function Validatecontact(theForm)
{
   var regexp;

   regexp = /^([0-9a-z]([-.\w]*[0-9a-z])*@(([0-9a-z])+([-\w]*[0-9a-z])*\.)+[a-z]{2,6})$/i;
   if (!regexp.test(theForm.Editbox3.value))
   {
      alert("Zlý formát emailu");
      theForm.usermail.focus();
      return false;
   }
   if (theForm.usermail.value == "")
   {
      alert("Zlý formát emailu");
      theForm.usermail.focus();
      return false;
   }
   return true;
}
</script>
<script type="text/javascript">
$(function(){
$(".search").keyup(function() 
{ 
var searchid = $(this).val();
var dataString = 'search='+ searchid;
if(searchid!='')
{
    $.ajax({
    type: "POST",
    url: "search.php",
    data: dataString,
    cache: false,
    success: function(html)
    {
    $("#result").html(html).show(); 
    }
    });   
}return false;    
}); 


jQuery("#result").live("click",function(e){ 
    var $clicked = $(e.target);
    var $name = $clicked.find('.name').html();
    var decoded = $("<div/>").html($name).text();

  var dataString = 'search='+ decoded;

  if(decoded!='')
  {
    $.ajax({
    type: "POST",
    url: "search2.php",
    data: dataString,
    cache: false,
    success: function(html)
    {
    $("#text").html(html).show(); 
    }
    });   
  }
});

jQuery("#result").live("click",function(e){ 
    var $clicked = $(e.target);
    var $name = $clicked.find('.name').html();
    var decoded = $("<div/>").html($name).text();
  var $email = $clicked.find('.email').html();
    var decoded2 = $("<div/>").html($email).text();
    $('#searchid').val(decoded); 
  $('#adresat').val(decoded2); 
});
jQuery(document).live("click", function(e) { 
    var $clicked = $(e.target);
    if (! $clicked.hasClass("search")){   
    jQuery("#result").fadeOut(); 
  document.getElementById('text').style.visibility='visible';
    }
});
$('#searchid').click(function(){
    jQuery("#result").fadeIn();
  document.getElementById('text').style.visibility='hidden';
});


});
</script>
</head>

<body>

<div class="content">

<form name="contact" method="post" accept-charset="UTF-8" action="<?php echo basename(__FILE__); ?>" enctype="multipart/form-data" id="Form1" onsubmit="return Validatecontact(this)">

<span style="color:#000000;font-family:Arial;font-size:13px;">Prevádzka :</span>
<input type="text" class="search" id="searchid" placeholder="Search for place" />  <br />
<div id="result">
</div>

<span style="color:#000000;font-family:Arial;font-size:13px;">Váš Email:</span>
<input type="text" id="usermail" name="email" value="">                            <br />

<span style="color:#000000;font-family:Arial;font-size:13px;">Opíšte kód z obrázka:</span></div>
<img src="captcha1.php" alt="Nový obrázok" title="Nový obrázok" style="cursor:pointer;" onclick="this.src='captcha1.php?'+Math.random()">
<input type="text" id="Captcha1Edit" name="captcha_code" value="">

<br />
<br />

<input type="text" id="adresat" name="adresat" value="" disabled>    
<input type="submit" id="submit" name="" value="Odoslať">
</form>

</div>

Thanks a lot for help.