How to remove an email message in Maildir from PHP?

I'm going crazy with a little problem with Maildir and PHP. I need to check the APACHE_RUN_USER's Maildir and parse delivery-status messages.

The problem removing message after reading; i noticed that Zend_Mail_Storage_Maildir->removeMessage() is still a stub.

try {   
    $mailbox = new Zend_Mail_Storage_Maildir( array('dirname' =>    '/home/' . $_ENV['APACHE_RUN_USER']  . '/Maildir/') );

    foreach ($mailbox as $id => $message) {

        // seen flag
        if ($message->hasFlag(Zend_Mail_Storage::FLAG_SEEN)) { continue; }

        //get the unique id
        $uniqueid = $mailbox->getUniqueId($id); 

        //obtain message headers
        $headers = $message->getHeaders();

        //check if the original message was sent from this app and is a delivery-status
        $result = strpos($message, $id_header);
        if($result === false) { echo '1 mail skipped: ' . $uniqueid . '. <br />'; continue; }

        $result = strpos($headers['content-type'], 'delivery-status');
        //if no skip to the next mail
        if($result === false) { echo '1 mail skipped: ' . $uniqueid . '. <br />'; continue; }

        // if everything it's ok process it.

        // clear results
        $data = array();
        // foreach line of message
        foreach( preg_split('/(\r?\n)/', $message) as $line ){
            //clear results
            $matches = array();

            //perform matches on textlines
            if( preg_match('/^(.+)\:\s{0,1}(.+)$/', $line, $matches) ) {
                //grab intrested headers
                foreach( array('Action', 'Status', 'Remote-MTA', 'Diagnostic-Code', $id_header) as $header) {
                    if($matches[1] == $header) $data[$header] = $matches[2];
                }
            }
        }

        // *** I NEED TO DROP THE MESSAGE HERE ***

            // not working code ***
        $currentmessageid = $mailbox->getNumberByUniqueId($uniqueid);
        $mailbox->removeMessage($currentmessageid); 

        // *** I NEED TO DROP THE MESSAGE HERE ***


    // print out results
        echo '<pre class="email">';
        print_r( $data );
        echo '</pre>';  
    }

} catch (Exception $e) {
    echo $e;
}

How can I remove it by hand? Some workarounds?

Thanks.

In order of tawfekov answer I solved as follow:

Opening mailbox:

$mailbox = new Zend_Mail_Storage_Writable_Maildir( array('dirname' =>   '/home/' . $_ENV['APACHE_RUN_USER']  . '/Maildir/') );

Processing mail code:

    foreach ($mailbox as $id => $message) {
        $uniqueid = $mailbox->getUniqueId($id);

        /* ... mail processing code ... */

        // mark as read
        $currentmessageid = $mailbox->getNumberByUniqueId($uniqueid);
        $mailbox->setFlags($currentmessageid, array(Zend_Mail_Storage::FLAG_SEEN));

        // or uncomment to delete it
        //$mailbox->removeMessage($currentmessageid);
    }