I’ve been working on archiving emails. In my pursuit to find the easiest possible solution I came across smtp-sink. As posted on:
http://blog.malowa.de/2011/04/postfix-as-spam-trap-server.html
Also another interesting post:
http://serverfault.com/questions/451240/how-do-i-set-up-postfix-to-store-e-mail-in-a-file-instead-of-relaying-it
mentions using php as an executable script that would get called to process the email. This would be ideal in doing extra spam processing although php might end up eating more memory than doing it via smtp-sink.