Setting up Haraka is simple. First, we need to create the service:

$ haraka -i /path/to/haraka_test

That creates the directory haraka_test and creates config and plugin directories in there, and automatically sets the host name used by Haraka to the output of the hostname command.

This assumes that hostname gives you the correct host you want to receive mail for. If not, edit the config/host_list file. For example if you want to receive mail addressed to user@domain.com, add domain.com to the config/host_list file.

Finally just start Haraka:

$ haraka -c /path/to/haraka_test

And it will run.

However the big thing you want to do next is to edit the config/plugins file. This determines what plugins run in Haraka, and controls the overall behaviour of the server. By default the server is setup to receive mails for domains in host_list and deliver them via qmail-queue. Queueing to qmail is likely not what you need unless you have qmail installed, so this is likely the first thing you want to change.

Each plugin has documentation available via haraka -h plugins/<name>. Look there for information about how each plugin is configured, edit your config/plugins file, restart Haraka and enjoy!