PHP e-mail

<html>
<body> <center>
<?

$name_file = $_FILES['monfichier']['name']; 
$source=$_FILES['monfichier']['tmp_name'];

move_uploaded_file($source, "./".$name_file); 

$extension=get_extension($name_file);

$type="text/plain";
if($type=="doc")
{
   $type="text/vnd.ms-word";
}
else if($type=="xls")
{
   $type="text/vnd.ms-excel";
}

$type2="image/png";

if($extension=="gif")
{
   $type2="image/gif";
}
else if($extension=="bmp")
{
   $type2="image/bmp";
}

function get_extension($filename)
{
   $parts = explode('.',$filename);
   $last = count($parts) - 1;
   $ext = $parts[$last];
   return $ext;
}

//----------------------------------
// Construction de l'entête
//----------------------------------

if($_POST['to']!="")
{
$boundary = "-----=".md5(uniqid(rand()));
$header = "MIME-Version: 1.0\r\n";
$header .= "Content-Type: multipart/mixed; boundary=\"$boundary\"\r\n";
$header .= "\r\n";

$msg = "Je vous informe que ceci est un message au format MIME 1.0 multipart/mixed.\r\n";

$msg .= "--$boundary\r\n";

$msg .= "Content-Type: $type; charset=\"iso-8859-1\"\r\n";
$msg .= "Content-Transfer-Encoding:8bit\r\n";
$msg .= "\r\n";
$msg .= $_POST['souhait'];
$msg .= "\r\n";
$msg .= $_POST['Experience'];
$msg .= "\r\n";
$msg .= $_POST['ville'];
$msg .= "\r\n";
$msg .= $_POST['prenom'];
$msg .= "\r\n";
$msg .= $_POST['NOM'];
$msg .= "\r\n";
$msg .= $_POST['email'];
$msg .= "\r\n";


if($name_file!="")
{
$file = $name_file;
$fp = fopen($file, "rb");  
$attachment = fread($fp, filesize($file));
fclose($fp);

$attachment = chunk_split(base64_encode($attachment));


$msg .= "--$boundary\r\n";
$msg .= "Content-Type: $type2; name=\"$file\"\r\n";
$msg .= "Content-Transfer-Encoding: base64\r\n";
$msg .= "Content-Disposition: inline; filename=\"$file\"\r\n";
$msg .= "\r\n";
$msg .= $attachment . "\r\n";
$msg .= "\r\n\r\n";
$msg .= "--$boundary--\r\n";
}

$destinataire = $_POST['to'];
$expediteur   = $_POST['from'];
$reponse      = $expediteur;
echo "Mail envoyé à $destinataire";

mail($destinataire, $_POST['sujet'], $msg,
     "Reply-to: $reponse\r\nFrom: $expediteur\r\n".$header);

}

if($name_file!="")
{
unlink($name_file);
}
print("<br>\n");
print("<br><A href=./mail3.php target=\"principal\"><font size=2>Envoyer un autre mail</font></A>");
?>
</center>
</body>
</html>