cmc-sales/controllers/email_attachments_controller.php

<?php
class EmailAttachmentsController extends AppController {

	var $name = 'EmailAttachments';
	var $helpers = array('Html', 'Form');


function download($id) {
    Configure::write('debug', 0);
    $file = $this->EmailAttachment->findById($id);
    header('Content-type: ' . $file['EmailAttachment']['type']);
    header('Content-length: ' . $file['EmailAttachment']['size']);
    header('Content-Disposition: attachment; filename="'.$file['EmailAttachment']['name'].'"');
    ob_clean();
    flush();
    readfile($file['EmailAttachment']['filename']);
    exit();
	}

}