Configuring postfix to fight spam, 2012 edition

view full story

http://serverfault.com – I'm running a small (20 users, 30 mailman-lists) server with postfix. I think it's configured fine, more or less. I spent 2 days reading up on all kinds of material on postfix configuration, but I couldn't find any list of measures that are actually safe to enable/disable. For about every configuration option i found there were some people pro and some against it. This is my postfix configuration, can you give me simple measures on what to improve? alias_database = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases append_ (HowTos)