Counting unread messages

[jeff at virgin.net]

Hi All,

I need to be able to run something that counts the number of unread messages in 
an mbox file. Im not really bothered about how it gets the info - be it 
via a php function, shell script, arguments to a mail application, whatever. 
The final result will be called by a php script so its pretty flexible.

Any ideas? The messages can either be accessed by imap or plain old mbox parsing 
(prefered). I thought there would be some sort or argument that could be 
passed to something like mutt but google has drawn a blank.

Thanks
Jeff