function validateSingleEmail(txtin, txtout)
{
    var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;


    if (document.getElementById(txtin).value == '')
    {
        document.getElementById(txtout).innerHTML = "Email address required!";
        return false;
    }
    else if (reg.test(document.getElementById(txtin).value) == false)
    {
        document.getElementById(txtout).innerHTML = "Valid email address required!";
        return false;
    }
    else
    {
        return true;
    }
}