fullURL = parent.document.URL;
item = fullURL.substring(fullURL.indexOf('?')+5, fullURL.length);

if((fullURL.indexOf('?') > 0) && (item == "email%20added%20successfully")){
	alert("Your email address has successfully been added to our mailing list. Thanks!"); //Alert box!
}
if((fullURL.indexOf('?') > 0) && (item == "Please%20provide%20a%20valid%20email%20address.;")){
	alert("Please provide a valid email adress."); //Alert box!
}