[OT] How to run procmail on Maildir or mbox

[O Polite <m2@plusseven.com>]

I spent the morning moving to fetchmail/procmail for mail retrieval and
filtering.

I think I will be very happy with it indeed.

Kmail and Evolution will let the user "apply filters" on already
filtered messages so as to put them in some other folder. This is great
when you realize that some filters are wrong and a zillion messages have
gone in wrong folders.

Is there anyway to do the same thing with procmail, apply it on an mbox
or Maildir?

regards op