archive old mail (formail?)

Does anybody have a script, that I assume would use 
formail, that will take a list of files (my pine mailboxes)
and archive messages more than "n" days old or something?

--
g-r-a-t-e-f-u-l-l-y---[   email:<fishbowl(_at_)conservatory(_dot_)com>   
]---l-i-v-i-n-g
d-e-a-d-i-c-a-t-e-d---[ http://www.conservatory.com/~fishbowl ]-----l-i-g-h-t
Today's scientific question is: What in the world is electricity?
And where does it go after it leaves the toaster?  
        -- Dave Barry, "What is Electricity?"