Single-user, vanilla install with two exceptions: the install will check our
two whitelists and give a pass (-100) to any of our clients so we don't
bounce their mail.
I hope you're not actually considering bouncing spam. That statement
sounds like it.
Either jecect them at smtp time or silently delete
other then that. whitelist sounds very simple to me:
http://wiki.apache.org/spamassassin/ManualWhitelist
unless you want to query a database of couse.
i'm using a check in my exim router to let some customers' customers
bypass SA completly.