var xmlHttp;
var email;
var listID;

function createXMLHtppRequest(){	
    if(window.ActiveXObject){
    	xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else if(window.XMLHttpRequest){
    	xmlHttp = new XMLHttpRequest();
    }	
}
function newsletterRequest(email, listID){
    listID = listID
    email  = email
    if(isValidEmail(email)){
        startNewsltterRequest(email, listID)
    }
}
function startNewsltterRequest(email, listID){	         
	createXMLHtppRequest();		
	xmlHttp.open("GET", "/ajax-newsletter.php?email="+email+"&listID="+listID, true);	
	xmlHttp.onreadystatechange = callbackNewsletter;
	xmlHttp.send(null);
}
function callbackNewsletter(){
    if(xmlHttp.readyState==4){     
        alert(xmlHttp.responseText);
    }
}