如何解决“使用php邮件功能打开pdf文档失败”的问题？

Question

我需要帮助，当我尝试打开 pdf 文档时收到此消息“无法加载文档”。 预期：应用程序/pdf (.pdf)；找到：文本/纯文本 (.txt)

` $filenameee = $_FILES['id']['name'];
 // main header (multipart mandatory)
   $headers = "From: ".$fromname." <".$fromemail.">" . $eol;
   $headers .= "MIME-Version: 1.0" . $eol;
   $headers .= "Content-Type: multipart/mixed; boundary=\"" . $separator . "\"" . $eol;
   $headers .= "Content-Transfer-Encoding: binary";
   $headers .= "This is a MIME encoded message." ;
    $headers .="Content-Length:  . filesize($filenameee)";
    $headers .="Accept-Ranges: bytes" ;
    @readfile($filenameee);

    // message
  //$body = "--" . $separator . $eol;
  $body .= "Content-Type: text/plain; charset=\"iso-8859-1\"" . $eol;
  $body .= "Content-Transfer-Encoding: binary" . $eol;
  $body .= $message . $eol;
    // attachment
 $body .= "--" . $separator . $eol;
 $body .= "Content-Type: application/pdf; name=\"" . $filenameee . "\"" . $eol;
 $body .= "Content-Transfer-Encoding: binary" . $eol;
 $body .= 'Content-Disposition: inline; $filenameee="' . $filenameee . '"';
$body .= $content . $eol;

$body .= "</tbody></table>";
    
$body .= "</body></html>";`