function esEmail(campo) 
{
    var strMail = campo;
    var patMail = /^(.+)@(.+)$/; 
    var patUser = /^[a-zA-Z\d_-]+(\.[a-zA-Z\d_-]+)*$/;
    var patDomainIP = /^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/;
    var patDomain = /^[a-zA-Z\d_-]+(\.[a-zA-Z\d_-]+)+$/;
    var matchArray = strMail.match(patMail);
    if (matchArray == null) { return false; }
    var user = new String(matchArray[1]);
    var domain = new String(matchArray[2]);
    if (user.match(patUser) == null) { return false; }
    var IPArray = domain.match(patDomainIP);
    if (IPArray != null) {
        for (var i = 1; i <= 4; i++) {
            if (IPArray[i] > 255)
            { return false; } 
        }
        return true;
    }
    var domainArray = domain.match(patDomain);
    if (domainArray == null) { return false; }
    if (domainArray[domainArray.length - 1].length < 3 || domainArray[domainArray.length - 1].length > 4) { return false; }
    return true;
}



function ValidaOrdering() {

    var Navegador = navigator.appName;
    var EsIE = false;
    if (Navegador == 'Microsoft Internet Explorer')
        EsIE = true;

    var Email = null;
    
    if (!EsIE) {
        Email = document.getElementById('ctl00$ContentPlaceHolder1$' + 'tb_Email')
    }
    else {
        Email = document.getElementById('ctl00_ContentPlaceHolder1_' + 'tb_Email')
    }

    if (Email.value == "") {
        alert("Email required");
        Email.focus();
        return false;
    }

    if ((Email.value)) {
        if (!esEmail(Email.value)) {
            alert("Email format error");
            Email.focus(); 
            return false;
        }
    }


    return true;


    
}