function validate(email) {
   var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
   if(reg.test(email) == false) {
      return false;
   }
   return true;
}

function ajaxSubmit(){
        var email = document.getElementById("emailfield").value;
        var ajaxRequest;  // The variable that makes Ajax possible!

        if (validate(email)==false) {
          document.getElementById("formMessage").innerHTML = "Please enter a valid email address.";
          return false;
        }

        try{
                // Opera 8.0+, Firefox, Safari
                ajaxRequest = new XMLHttpRequest();
        } catch (e){
                // Internet Explorer Browsers
                try{
                        ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
                } catch (e) {
                        try{
                                ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
                        } catch (e){
                                // Something went wrong
                                alert("Your browser broke!");
                                return false;
                        }
                }
        }

        // Create a function that will receive data sent from the server
        ajaxRequest.onreadystatechange = function(){
                if(ajaxRequest.readyState == 4){
                        document.getElementById("formMessage").innerHTML = "Thank you for registering.";
                }
        }
        ajaxRequest.open("GET", "/saveemail.asp?email=" + email, true);
        ajaxRequest.send(null);
}