function validemailformat(email) {
    
    var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
    
    if (!filter.test(email)) {
        return false;
    } else {
        return true;
    }
}