File newFolder = folder.getNewFolder();
File curFolder = folder.getCurFolder();
String[] unseenMessages = curFolder.list(MaildirMessageName.FILTER_UNSEEN_MESSAGES);
String[] newUnseenMessages = newFolder.list(MaildirMessageName.FILTER_UNSEEN_MESSAGES);
if (newUnseenMessages == null || unseenMessages == null)
throw new MailboxException("Unable to count unseen messages in Mailbox " + mailbox,
new IOException("Not a valid Maildir folder: " + maildirStore.getFolderName(mailbox)));
int count = newUnseenMessages.length + unseenMessages.length;
return count;
}