Are there any good maildir manipulation utilities out there?

[Chris Green]

I'm looking for a tool which will allow me to search through a large
hierarchy of maildir messages and then provide actions to take on the
matched messages.

E.g. I might want to archive all messages older than a certain date
but archive them into a similar hierarchy rather than to just a single
archive directory.

Or I might want to search for all messages from a certain person (or
business) and move them into a single folder.

I already use mairix for searching for messages but it doesn't offer
the actions function I'm after.  

Before I start creating something for myself is there anything out
there which can do this sort of thing?

-- 
Chris Green