function doRegistration(email) {
    var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
    if (reg.test(email) == false) {
        alert('The email address your entered is invalid please try again');
        return false;
    }
    alert('Your email address has been submitted. Thank you');
    return true;
}