function email_Validate(sender, args) {
        var txt = document.getElementById(sender.controltovalidate);
    var result;
    result = checkEmail(txt.value);
    args.IsValid = result;
}

function checkEmail(email) {
    var sRegEx = "^([a-zA-Z0-9_\\-\\.]+)@((\[[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.)|(([a-zA-Z0-9\\-]+\\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$";

    if (email.search(sRegEx)!=-1) {
        return true;
    }
    else {
        return false;
    }
    
}