protected function getDefaultMessageFilter()
    {
        $filter = 'all';
        $db = \Database::get();
        $count = $db->GetOne('select count(cpa.paID) from ConversationPermissionAssignments cpa
            inner join PermissionAccess pa on cpa.paID = pa.paID
            inner join ConversationPermissionAddMessageAccessList cpl on pa.paID = cpl.paID
            where paIsInUse = 1 and permission = "U"');
        if ($count > 0) {
            $filter = 'unapproved';
        }

        return $filter;
    }