在Constant Contact中查看电子邮件地址

I can't find a damned bit of documentation for using the Constant Contact REST API to check if an email address is in a list or not.

The following seems to be completely useless:

include_once('cc_class.php');
$ccContactOBJ = new CC_Contact("basic", $cckey, $ccuser, $ccpass);
if(($_SERVER['REQUEST_METHOD']=="POST") && !empty($_REQUEST['member-submit'])) {
$contact = $ccContactOBJ->getSubscribers(urlencode($_POST['MemberEmail']));

if (empty($contact['items'])) {
    $message = 'You are not listed in our database.';      
}
else {
    $message = 'You are already listed in our database';     
}
echo $message; 

}

Anyone have ANY idea how to return a true or false value?