Haraka - a Node.js Mail Server
Haraka can be used either as an inbound SMTP server, and is designed with good anti-spam protections in mind (see the plugins directory), or it can be used as a lightweight outbound mail server (run it on port 587 with an "auth" plugin to authenticate your users).
What Haraka doesn't do is fully replace your mail system. It doesn't do mail queueing or delivery with retries. For that we expect you to have something like postfix, exim or qmail installed already. It also doesn't have an inbound message store, for that you should probably run an IMAP server.
Why Use Haraka Then?
Haraka's primary purpose is to provide you with a much easier to extend mail server than most available SMTP servers out there such as Postfix, Exim or Microsoft Exchange, yet while still running those systems for their excellent ability to deliver mail to users.
The plugin system makes it trivial to code new features. A typical example might be to provide qmail-like extended addresses to an Exchange system, whereby you could receive mail as firstname.lastname@example.org, and yet still have it correctly routed to email@example.com. This is a few lines of code in Haraka, or maybe someone has already written this plugin.
Plugins are already provided for running mail through SpamAssassin, checking for known bad HELO patterns, checking DNS Blocklists, and watching for violators of the SMTP protocol via the "early_talker" plugin.
Furthermore Haraka comes with a simple plugin called "graph" which shows you real-time charts of which plugins rejected the most mail, allowing you to easily fine-tune your list of plugins to more effectively stop spam.
Haraka requires node.js to run.
Starting Haraka is simple. First edit the supplied config/smtp.ini file to determine which host and port to run on. Then edit config/me to give your server an appropriate name (usually your hostname is correct, but in a multi-server setup you may wish to use a unified name).
Finally just start Haraka:
And it will run.
However the big thing you need 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. For example if you want to proxy connections to a backend SMTP server you want to set your queue plugin to be queue/smtp_proxy. Have a good look over the plugins in the plugins/ directory to see what is applicable to your setup.
As a typical example here is what I have on my personal server:
dnsbl data.nomsgid data.noreceived data.signatures data.uribl early_talker graph helo.checks mail_from.is_resolvable mail_from.nobounces max_unrecognized_commands rcpt_to.in_host_list rcpt_to.max_count rdns.regexp queue/qmail-queue
However this may not be to your taste. Also bear in mind that each plugin often has configuration of its own. Look at the code, and if it's not obvious just email me at firstname.lastname@example.org and I'll give you some assistance.