email com anexos

Bom dia colegas,

Utilizo num form um script para envio de emails com anexo. ate aí tudo bem. Agora preciso de o alterar para enviar um arquivo que foi enviado para o servidor. Ou seja, o admin do site, faz upload de um arquivo PDF. Dias mais tarde decide envia-lo por email.

Tenho testado com varios scripts "ja feitos" altero para o que teoricamente preciso e envia o anexo, mas quando tento abrir o anexo no outlook, esta sempre danificado. ja tentei enviar arquivos .txt, .pdf e .zip. Tudo danificado.

Aqui vai o script:

<?php //define the receiver of the email $to = meuemail@xpto.com'; //define the subject of the email $subject = 'email com anexo'; //create a boundary string. It must be unique //so we use the MD5 algorithm to generate a random hash $random_hash = md5(date('r', time())); //define the headers we want passed. Note that they are separated with \r\n $headers = "From: $to\r\nReply-To: $to"; //add boundary string and mime type specification $headers .= "\r\nContent-Type: multipart/mixed; boundary=\"PHP-mixed-".$random_hash."\""; //read the atachment file contents into a string,//encode it with MIME base64,//and split it into smaller chunks$attachment = chunk_split(base64_encode(file_get_contents('attachment.zip'))); //define the body of the message. ob_start(); //Turn on output buffering ?> --PHP-mixed-<?php echo $random_hash; ?> Content-Type: multipart/alternative; boundary="PHP-alt-<?php echo $random_hash; ?>" --PHP-alt-<?php echo $random_hash; ?> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bitHello World!!! This is simple text email message. --PHP-alt-<?php echo $random_hash; ?> Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: 7bit<h2>Hello World!</h2> <p>This is something with <b>HTML</b> formatting.</p> --PHP-alt-<?php echo $random_hash; ?>-- --PHP-mixed-<?php echo $random_hash; ?> Content-Type: application/zip; name="attachment.zip" Content-Transfer-Encoding: base64 Content-Disposition: attachment <?php echo $attachment; ?> --PHP-mixed-<?php echo $random_hash; ?>-- <?php //copy current buffer contents into $message variable and delete current output buffer $message = ob_get_clean(); //send the email $mail_sent = @mail( $to, $subject, $message, $headers ); //if the message is sent successfully print "Mail sent". Otherwise print "Mail failed" echo $mail_sent ? "Mail sent" : "Mail failed"; ?>

Alguma ideia?