Unread messages should be in the new subdirectory of Maildir, and read messages in cur. Not sure about using those modules, but that's how Maildir works. See http://cr.yp.to/proto/maildir.html.

That's basically correct but... at least with my Postfix / Courier IMAP / Squirrelmail setup, as soon as I use Squirrelmail any messages in the new dir are moved to cur - even if they're not read yet. When the message is read, :2,S is appended to the file name in cur. This is best explained at http://www.courier-mta.org/?maildir.html . Other MTA/IMAP server/MUA combinations may handle this differently.