[mew-int 3030] New mails notification

Diep Pham Van <[email protected]> Thu, 08 Dec 2011 10:24:49 +0700 (ICT)

Newsgroups	gmane.mail.mew.general
Message-ID	<[email protected]>

Hi,
I'm a new mew user, I've searched all around but cannot find out the solution.
I have:

    (setq mew-use-biff t)
    (setq mew-use-biff-bell t)
    (setq mew-biff-interval 5)

in my .mew.el. 
The question is: "How can I call a function or an external program when new mails arrive?"

Thanks for reading.