public function validateFeaturedImageServer($featuredImageServer) {

        // if there is no featured_image_server, then there is no featured image -- which is ok
        if ((!$featuredImageServer) || ($featuredImageServer == "") ) {
            return "passed";
        }

        // not acceptable file extension
        if (!$this->isImageFileExtensionKosher($featuredImageServer)) {
            return "The image file you selected on your server, ".$featuredImageServer.",  is not an accepted image file type.";
        }

        // file NOT already exists on the server
        if (!$this->doesImageFileExistOnServer($featuredImageServer)) {
            return "The image file you selected on your server, ".$featuredImageServer.", does NOT actually exist on the server.";
        }

        return "passed";
    }