public function build($boundary, $eol = "\r\n")
{
$attachment = $eol . '--' . $boundary . $eol . 'Content-Type: file; name="' . $this->basename . '"' . $eol . 'Content-Transfer-Encoding: base64' . $eol . 'Content-Description: ' . $this->basename . $eol . 'Content-Disposition: attachment; filename="' . $this->basename . '"' . $eol . $eol . $this->encoded . $eol . $eol;
return $attachment;
}