OT: Does a proxy IMAP server exist?

[Tom Horsley]

Just curious if such a thing as a "proxy IMAP" server exists? (Preferably
already available in some rpm I can install on fedora :-).

What is that, you ask?

I'd like to continue to keep my mail on the IMAP server at work, but I'd
like better spam filtering than the server-side rules provide.

What I'd really like to have is something on my desktop that acts like
an IMAP server, but really forwards requests to the main server, however
it does allow me to do procmail/spamassassin/bogofilter processing of the mail
on the corporate IMAP server so I can delete obvious spam, etc. before
anything talking to my local IMAP server even sees it.