this code of mine:

    $noreply = new Zend_Mail_Storage_Imap(array(
        'host'     => IMAPSERVER_NOREPLY_HOST,
        'user'     => IMAPSERVER_NOREPLY_LOGIN,
        'password' => IMAPSERVER_NOREPLY_PASSWORD,
        'port'     => IMAPSERVER_NOREPLY_PORT));
        
    lg('Es liegen '.$noreply->countMessages().' Nachrichten in der Noreply-Mailbox');

led to a warning: 'invalid argument supllied for foreach()' in Zend_Mail_Protocol_Imap line 829 in case that this mailbox contained zero messages. lg() is just my logfile-function to gather Information.

I helped myself, fixing the method in Zend_Mail_Protocol_Imap like this:

    public function search(array $params)
    {
        $response = $this->requestAndResponse('SEARCH', $params);
        if (!$response) {
            return $response;
        }

    /* start bugfix */
        if (!is_array($response)) $response = array($response);
    /* end bugfix */
    
        foreach ($response as $ids) {
            if ($ids[0] == 'SEARCH') {
                array_shift($ids);
                return $ids;
            }
        }
        return array();
    }