日语电子邮件附件名称乱码PHP邮件

Question

The code below works fine in Google Mail and Yahoo Mail. Attachment filenames work fine but in Hotmail attachments of Japanese filenames are garbled.

// multipart boundary
$message =  "--{$mime_boundary}
" . "Content-Type: ".$contentType."; charset=\"iso-8859-2,utf-8\"
"  .
"Content-Transfer-Encoding: 7bit

" . $message . "

";

//---- dummy size
$tempsize= 1024 ;
//---- dummy size

$ctrFileName = 0;
// preparing attachments
if(count($attachment) > 0){
    foreach ($attachment as $file_data) {
        $message .= "--{$mime_boundary}
";
        $data = chunk_split(base64_encode($file_data));
        $message .= "Content-Type: application/octet-stream; name=\"".$filenameattach[$ctrFileName]."\"
" .
        "Content-Description: ".$filenameattach[$ctrFileName]."
" .
        "Content-Disposition: attachment;
" . " filename=\"".$filenameattach[$ctrFileName]."\"; size=".$tempsize.";
" .
        "Content-Transfer-Encoding: base64

" . $data . "

";
        $ctrFileName++;
        //$message .= "--{$mime_boundary}--";
    }
} else {

    $message .= "--{$mime_boundary}--";
}

//$message .= "--{$mime_boundary}--";
//$returnpath = "-f" . $fromaddress;


$success = @mail($to, $subject, $message, $headers);