//Make sure that email address contains required characters @ and .
function validateEmail(sender, args) {

    var containsAt = false;
    var containsDot = false;
    var address = args.Value.toString();
    var addressLength = address.length;
    
    for (var i = 0; i < addressLength; ++i) {
        if (address.substr(i, 1) == '@') {
            containsAt = true;
        }
        if (address.substr(i, 1) == '.') {
            containsDot = true;
        }
    }
    if (containsDot == true && containsAt == true) {
        args.IsValid = true;
    } else { args.IsValid = false; }
}