An event driven SMTP server
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Haraka - a Node.js Mail Server

Haraka is an SMTP server which uses a plugin architecture to implement most of its functionality. It uses a highly scalable event model to be able to cope with thousands of concurrent connections. Plugins are written in Javascript using Node.js, and as such perform extremely quickly. The core Haraka framework is capable of processing thousands of messages per second on the right hardware.

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 an outbound mail server - the most common way of doing this is by running it on port 587 with an "auth" plugin to authenticate your users.

A full mail system for end users is vastly complicated, and so Haraka makes no attempt to be an IMAP server, figure out where mails should be delivered, or implement any of the functionality of a mail store. As such it is common to have a backend mail server which Haraka delivers to for that sort of functionality - Exchange, Postfix, Dovecot or Courier would be examples of such systems.

Haraka does have a scalable outbound mail delivery engine built in. Any mail marked as relaying (such as via an auth plugin) will automatically be queued for outbound delivery.

Join the Mailing List

To get started with Haraka and ask questions about it, please join the mailing list: - the mailing list is implemented as a Haraka plugin.


Getting started with Haraka

Why Use Haraka?

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, and yet still have it correctly routed to 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.

Installing Haraka

Haraka is written in Javascript and requires node.js to run.

Installation is very simple via npm:

$ npm install -g Haraka

That will provide you with a haraka binary which allows you to setup the service.

Running Haraka

Setting up Haraka is simple. Firstly 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, add 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!

Feel free to write to the mailing list with any questions. Or use github "Issues".

Running from git

If you are unable to use npm to install Haraka, you can run from git by following these steps:

First clone the repository:

$ git clone
$ cd Haraka

Edit config/plugins and config/smtp.ini to specify the plugins and config you want.

Finally run Haraka:

$ node haraka.js


Haraka is fast, due to the nature of using the v8 Javascript engine, and it is scalable due to using async I/O everywhere. On my local system I have managed to scale it up to 5000 emails per second (with minimal plugins).

I welcome other performance evaluations.

License and Author

Haraka is MIT licensed - see the LICENSE file for details.

Haraka is a project started by Matt Sergeant, a 10 year veteran of the email and anti-spam world. Previous projects have been the project leader for SpamAssassin and a hacker on Qpsmtpd, a perl based mail server which is quite similar to Haraka (but not as fast due to perl being slower than Javascript).