Email migration script

[matt-urrlRJtNKRMsHrnhXWJB8w at public.gmane.org (Matt Shields)]

Does anyone have a script that will either POP3 or IMAP to a source mail
server and copy to a destination mail server?  Normally I've done this by
just using the client's credentials to copy mailboxes one at a time with
Thunderbird, but I have a client with a couple hundred mailboxes.  The
script can be either PHP, Bash, Perl, Ruby or Python.  It can be as simple
as it only takes 1 mail box at a time, and I'll write my own wrapper around
it.

-matt