The program that makes decisions about how to deliver (or not deliver) email that has made it through the highest level blacklists is called procmail. Thus we will need to write some procmail rules in its peculiar language to implement our whitelists and blacklists.
A typical procmail rule has 3 lines with a structure that looks very similar to the following.
line 01: :0: (opening of new rule)
line 02: * [matching-rule]
line 03: destination-folder
Sample Whitelist Rules
* ^From: .*firstname.lastname@example.org
Sample Blacklist Rules
* ^From: .*email@example.com