try new mailboxcheck

zimbraAddressAvailable.php

@@ -5,11 +5,8 @@ if(substr($host, 0 - strlen($allowed_host)) != $allowed_host) {
   die("This file cannot be accessed directly");
 }
 
-use WHMCS\Database\Capsule;
 define("CLIENTAREA", true);
 require_once(__DIR__ . '/../../init.php');
-require_once(ROOTDIR . '/includes/dbfunctions.php');
-require_once dirname(__FILE__) . '/zimbraSingle.inc';
 use WHMCS\Database\Capsule;
 
 $whmcs = App::self();