Dropping spam into a different a custom mailbox

[Amir Sela]

Hi,
I'm using MailScanner+SpamAssassin+Postfix. I couldn't find anywhere
in the docs a way
to setup my system such that instead of (or in addtion to) appending
the {spam?} string to
subject lines, I will get all spam redirected to some mbox inside the
user's home directory.
I tried using Procmail inside postfix, but as soon as I don't get any
mail at all.
Filtering on the client-side is not an option in my case, so I must do
this server-side.
What's the best way of doing that with my setup?
I simply didn't see anything pertinent I can use in "Spam Actions ="
to deliver to a custom
mailbox.
Thanks a lot,

 -amir