"By using Transports with Postfix, you can add a lot of flexibility and customization to how your mail is handled. In Part Two of this series, I described how to use Transports in conjunction with the spamc program to tag email as either spam or ham. While spamc does a great job at tagging, it doesn't provide any features beyond that--such as delivery options, quarantining, and virus scanning. As a result, more robust scripts and packages have been created to provide these extra features. Before I cover some of those packages, I'd like to explain how to write a custom spam filtering script..."
