PHP mail - checkboxes values do not appears in email

[SIZE=3]I have a PHP form which emails me all the fields to my email[/SIZE]
[SIZE=3]Text fields, radio button, option box and message fields works fine alone with attachment. But I only cannot get ALL checked values form checkboxes.[/SIZE]
[SIZE=3](When I select one checkbox, I get the result, but if I check, more than one, then I get only the last checkbox value)[/SIZE]
[SIZE=3]Need help[/SIZE]
[SIZE=3] [/SIZE]
[SIZE=3]My PHP Code is:[/SIZE]

 
<?php 
$to = "[my real email]"; 
$subject = " PHP Mail FOrm Practice "; ;
$name = $_REQUEST['name'] ; 
$email = $_REQUEST['email'] ; 
$system = $_REQUEST['system'] ;
$gender = $_REQUEST['gender'] ;
$language = $_REQUEST['language'] ;
$message = $_REQUEST['message'] ;
$url = "T6 - EGGI - Application for Job"; 
$details = "
 URL - Form: $url

   Subject: $subject

   Name: $name

   email: $email

   system: $system 

   gender: $gender 

   language: $language 

   message: $message 

  ";
ini_set("sendmail_from", $email);
// Obtain file upload vars
$fileatt      = $_FILES['fileatt']['tmp_name'];
$fileatt_type = $_FILES['fileatt']['type'];
$fileatt_name = $_FILES['fileatt']['name'];
$headers = "From: $email";
if (is_uploaded_file($fileatt)) {
  // Read the file to be attached ('rb' = read binary)
  $file = fopen($fileatt,'rb');
  $data = fread($file,filesize($fileatt));
  fclose($file);
  // Generate a boundary string
  $semi_rand = md5(time());
  $mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";
  
  // Add the headers for a file attachment
  $headers .= "
MIME-Version: 1.0
" .
              "Content-Type: multipart/mixed;
" .
              " boundary=\"{$mime_boundary}\"";
  // Add a multipart boundary above the plain message
  $message = "This is a multi-part message in MIME format.

" .
             "--{$mime_boundary}
" .
             "Content-Type: text/plain; charset=\"iso-8859-1\"
" .
             "Content-Transfer-Encoding: 7bit

" .
             $details . "

";
  // Base64 encode the file data
  $data = chunk_split(base64_encode($data));
  // Add file attachment to the message
  $message .= "--{$mime_boundary}
" .
              "Content-Type: {$fileatt_type};
" .
              " name=\"{$fileatt_name}\"
" .
              //"Content-Disposition: attachment;
" .
              //" filename=\"{$fileatt_name}\"
" .
              "Content-Transfer-Encoding: base64

" .
              $data . "

" .
              "--{$mime_boundary}--
";
}
// Send the message
$ok = mail($to, $subject, $message, $headers);
if ($ok) {
  echo "<p>Mail sent! Yay PHP!</p>";
} else {
  echo "<p>Mail could not be sent. Sorry!</p>";
}
?>

[SIZE=3] [/SIZE]
[SIZE=3][/SIZE]
[SIZE=3]My HTML Code is:[/SIZE]

 
<html>
<body>
<table width="900" border="0" align="center" cellpadding="0" cellspacing="0" bgcolor="#FFFFFF">
  <tr>
    <th scope="col"><table width="100%" border="0" cellspacing="0" cellpadding="0">
      <tr>
        <th valign="top" bgcolor="#DDE8F7" scope="col"><table width="100%" border="0" cellspacing="0" cellpadding="0">
          <tr>
            <th scope="col"><h1>Contact us form</h1>
                <form action="contactus.php" method="post" enctype="multipart/form-data">
                  <br />
                  <table width="58%" border="0" align="center" cellpadding="0" cellspacing="0">
                      <tr>
                        <td width="153" height="1" align="left" valign="middle">Full Name:</td>
                        <td width="333" align="left"><label for="name"></label>
                            <input type="text" name="name" id="name" /></td>
                      </tr>
                      <tr>
                        <td align="left" valign="middle">Persoanl Email:</td>
                        <td align="left"><input type="text" name="email" id="email" /></td>
                      </tr>
                      <tr>
                        <td width="153" height="2" align="left" valign="middle">Operating System</td>
                        <td align="left"><label for="system"></label>
                          <select name="system" id="system">
                            <option value="windows">Windows</option>
                            <option value="linux">Linux</option>
                            <option value="mobile">Mobile</option>
                                                    </select></td>
                      </tr>
                      <tr>
                        <td align="left" valign="middle">Gender</td>
                        <td align="left"><input type="radio" name="gender" value="Male" checked="checked">
                          Male
                          <input type="radio" name="gender" value="Female">
                          Female </td>
                      </tr>
                      <tr>
                        <td height="1" align="left" valign="middle">Languages:</td>
                        <td align="left">
                        
                          <input type="checkbox" name="language"    value="English">                          English <br/>
                          <input type="checkbox" name="language"  value="Pashto">                          Pashto <br/>
                          <input type="checkbox" name="language"  value="Dari">                          Dari <br/>                        </td>
                      </tr>
                      <tr>
                        <td height="40" align="left" valign="middle">Message:</td>
                        <td align="left"><label for="message"></label>
                        <textarea name="message" id="message" cols="45" rows="5"></textarea></td>
                      </tr>
                      <tr>
                        <td height="40" align="left">&nbsp;</td>
                        <td align="left"><label for="button"></label>
                          File Attachment: 
                        <input type="file" name="fileatt" />                        </tr>
                      <tr>
                        <td height="40" align="left">&nbsp;</td>
                      <td align="left"><input type="submit" value="Send" />                      </tr>
                    </table>
                  </form>
                </th>
          </tr>
        </table></th>
        </tr>
    </table>
 </th>
  </tr>
</table>
</body>
</html>


[SIZE=3] thanks[/SIZE]