upload file with front-end submission and forward the data in an email

In case anyone needs this, here is my solution:

if ($_FILES) {

    function insert_attachment($file_handler, $post_id, $setthumb = 'false') {
    if ($_FILES[$file_handler]['error'] !== UPLOAD_ERR_OK) __return_false();

    require_once(ABSPATH . "wp-admin" . '/includes/image.php');
    require_once(ABSPATH . "wp-admin" . '/includes/file.php');
    require_once(ABSPATH . "wp-admin" . '/includes/media.php');

    $attach_id = media_handle_upload( $file_handler, $post_id );

    //get url
    $attachment_url = wp_get_attachment_url($attach_id);
    add_post_meta($post_id, '_file_paths', $attachment_url);

    $attachment_data = array(
    'ID' => $attach_id
    );

    wp_update_post($attachment_data);


    if ($setthumb) update_post_meta($post_id, '_thumbnail_id', $attach_id);
    return $attach_id;

}

    foreach ($_FILES as $file => $array) {
        $newupload = insert_attachment($file, $pid);
        //getting the url for the new upload
        $attachment_url = wp_get_attachment_url($newupload);
    }

}