No. I enabled some of the plugins because they contained the hooks that the code indicated it was trying to execute - for example, looking for a startup function, I found it in the autologin and http_authenticate plugins, and in rcmail.php - however, the function in rcmail is not a hook, and is called early.
This is a problem because the code in index.php expects a call to the hooked up plugin:
// trigger startup plugin hook
$startup = $RCMAIL->plugins->exec_hook('startup', array('task' => $RCMAIL->task, 'action' => $RCMAIL->action));
$RCMAIL->set_task($startup['task']);
$RCMAIL->action = $startup['action'];
without this call, task and action are never set and so the user is never validated.
There are also calls to template_object_* hooks that simple don't exist anywhere in the code that I can find.
The only conclusion I can come to at this stage is the tar (0.3stable - yeah right) is not so stable or incomplete. I was hoping for a squirrelmail replacement, but so far have been disappointed.
I am going to continue digging into the code, but if someone can point me in the right direction, it would save a lot of time.
