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

Haraka is a plugin capable SMTP server. 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.

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 (run it on port 587 with an "auth" plugin to authenticate your users).

What Haraka doesn't do is fully replace your mail system (yet). It currently has no built-in facilities for mapping email addresses to user accounts and delivering them to said accounts. For that we expect you to keep something like postfix, exim or any other user-based mail system, and have Haraka deliver mail to those systems for that mapping. However nothing is stopping someone writing a plugin which replicates that facility - it just has yet to be done.

Haraka does have a scalable outbound mail delivery engine in the deliver plugin, which should work well for most sites.

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.

Running Haraka

Haraka is written in Javascript and 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:

node haraka.js

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:


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 and I'll give you some assistance.


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).

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