In essence, the Haraka system is powered by one of the world's most advanced, scalable network architectures. The open framework provides you with the tools you need to prevent spam and malware entering your network, and lowering your cost of improving and monitoring your mail systems.
In short, Haraka provides you with the free alternative to commercial high performance mail software, far out-performing open source alternatives, leaving you with the resources you need to compete on your core strengths, while giving you the flexibility to deal with email the way you see fit.
Installation is simple, just install Node.js and npm and type:
npm install -g Haraka