This article explain simple way to set up RBL anti-spam filter for Postfix MTA.
RBL stands for Real-time Blackhole List. RBL is a special DNS-based service which supports database of spam-compromised IP adresses. Some mail servers, including Postfix support RBL checking of sender IP(and blocking mail), which allows to reduce amount of incoming spam.
To enable RBL anti-spam filtering, add following line to main.cf config file:
config file: main.cf
This example uses cbl.abuseat.org RBL service, which filters considerable quantity of spam, while passing through nearly all non-spam letters.
Some others RBL services may block more spam, however, there is also a chance that they will not pass a legal, non-spam letter(false positive result).
Use search engine to find other RBL lists. Example queries: