Amir - the stock configuration settings will filter SPAM to a high degree without any intervention on your part. Pick a conservative number, or use the pre-built SPAM sensitivity of "medium", and you will block huge amounts of SPAM.
If you optionally enable the RBLs you will be pleased.
It's worth testing and it does work well without anything else. The pattern matching is also easy to configure. The whole package works well without any intervention.
regards,
patrick