Comment 21 for bug 1447107

It´s solved.

Replace this lines at the class.attachment.php in that method outputDowload():

    $filename = Mime_Helper::encodeQuotedPrintable($filename);
    header("Content-Disposition: {$disposition}; filename=\"{$filename}\"");

by this lines:

$filename = rawurlencode($filename);
header("Content-Disposition: {$disposition}; filename=\"{$filename}\"; filename*=UTF-8''{$filename}");