function validEmail(email) {
    if (email=="" || email== null) {
        return false;
    } else {
        var emailReg = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,6}|[0-9]{1,3})(\]?)$/; // valid
        if (!emailReg.test(email)) { // if syntax is valid
            return false;
        }
        return true;
    }
}

function chkReg(registration) {
    if (document.registration.regName.value=="") {
        alert(errorNoUserName);
        document.registration.regName.focus();
        return false;
    
    } else if (document.registration.regMail.value=="") {
        alert(errorNoEmail);
        document.registration.regMail.focus();
        return false; 
        
    } if (!validEmail(document.registration.regMail.value)) {
        alert(errorNoValidEmail);
        document.registration.regMail.focus();
        return false;
                
    }
    
    return true;
}