Access mailbox with php

I want to access my mailbox using php but cannot get a connection to work.

$mailbox = imap_open($url, $id, $pwd);

Does the server url require a port number?

<?php
$url = "{mail.de.opalstack.com:993/imap/ssl}INBOX";
$id = "mailboxname";
$pwd = "password123";
$mailbox = imap_open($url, $id, $pwd);

Many thanks!

skyrack curious. how do you make use of this php access to yr mailbox?