I have problems with this plugin, I have checked and my server do support the RECENT-flag but still no notifications are shown.
Maybe its a cmpatibility issue with Roundcube 0.8+?
It seems this part is the problem:
(array) $uids = $RCMAIL->imap->search_once($args['mailbox'], 'RECENT', true);
foreach($uids as $uid) {
$message = new rcube_message($uid);
$from = $message->sender['name'] ? $message->sender['name'] : $message->sender['mailto'];
$subject = $message->subject;
if(strtolower($_SESSION['username']) == strtolower($RCMAIL->user->data['username']))
{
$RCMAIL->output->command("plugin.showNotification", array(
'duration' => $RCMAIL->config->get('html5_notifier_duration'),
'subject' => $subject,
'from' => $from,
'uid' => $uid
));
}
}