Auto-Forwarding Tool for IMAP?

I’m looking for a utility to scan an IMAP account and auto-forward any messages from person A to a another account. Of course, if Mozilla supported auto-forward, I wouldn’t have to seek this functionality elsewhere ;).

As a halfway measure, I think I could set a filter in Mozilla to copy messages from person A to an intermediary IMAP mailbox, but that doesn’t do me much good since the destination account is POP3.

Even if there were some utility that could foward e-mail from an IMAP account but could only forward the entire account, then I might still be able to make use of that in concert with Mozilla copying messages to that intermediary IMAP account.

And, yeah, I suppose this would be easy with Linux. Stop snickering ;).