Haraka (software)

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Developer(s) Matt Sergeant, 61 others
Initial release May 2011
Stable release
2.8.8 / July 20, 2016
Development status Active
Written in Node.js, Javascript
Operating system Unix-like, Windows
Type Mail transfer agent
License MIT License
Website http://haraka.github.io/

Haraka is an open source[1] SMTP server. Its architecture is plugin-oriented[2] and event-driven. The server and its plugins are written in Javascript[3] using the Node.js framework.[4]

Haraka follows a plugin model, implementing a very lightweight SMTP core and providing developers hooks into the mail flow.[5] Almost all of Haraka's functionality is built as plugins.

Through its use of the V8 JavaScript engine and asynchronous I/O, the author claims the server is capable of handling thousands of messages per second.[6]

Bounce.io announced that they regularly handle 2 to 5 thousand simultaneous SMTP connections[7] with Haraka.

Typical Usage[edit]

Haraka is frequently used as a filtering MTA in front of other MTAs that lack the performance and/or filtering capabilities of Haraka. Craigslist uses Haraka[8] to handle inbound and then forward validated connections to Postfix.[9] Bounce.io similarly uses Haraka to accept incoming messages and deliver them to their application engine. Mail Toaster 6 uses Haraka[10] similarly to accept incoming mail and forward to a qmail based message store.


  • SMTP Authentication via LDAP,[11] vpopmaild,[12] flat_file, or SMTP proxy.
  • Access control by domain, IP, sender, or recipient.[13]
  • Bounce validation, optionally blocking forged or invalid bounces.
  • Virus filtering with ClamAV and AVG
  • ASN lookups and filtering
  • Forward Confirmed reverse DNS validation
  • GeoIP reporting and optional filtering
  • Detection of remote Operating System
  • Header validation: make sure required headers are present, singular headers are not duplicated, and values are credible.
  • URIBL lookups of senders IP, helo hostname, envelope sender, and message contents
  • DKIM validation and signing (native)
  • DNSBL support
  • Early talker detection
  • HELO hostname validation (8 tests)
  • Karma, a heuristics scoring engine that weighs the results of all plugins and smites or blesses each connection.
  • Messagesniffer (requires SNF installation)
  • Rate limiting, by host, sender, or recipient
  • Recipient validation in flat file, LDAP, Redis, or qmail-deliverabled.
  • SpamAssassin, via spamd.
  • SPF (native)
  • TLS / SSL
  • Overload detection and automatic deferral of new connections.

See also[edit]

External links[edit]


  1. ^ "Haraka License". GitHub. Retrieved 14 February 2015. 
  2. ^ "Haraka Plugins". Haraka Source Code. GitHub. Retrieved 15 February 2015. 
  3. ^ "Haraka Language Statistics". Haraka Source Repository. GitHub. Retrieved 15 February 2015. 
  4. ^ http://haraka.github.io/README.html
  5. ^ "Writing Haraka Plugins". Haraka Docs. GitHub. Retrieved 15 February 2015. 
  6. ^ "Haraka Readme". Haraka. GitHub. Retrieved 15 February 2015. 
  7. ^ "Tech Shoutout - Haraka at bounce.io". Bounce.io. bounce.io. Retrieved 15 February 2015. 
  8. ^ "Craigslist Uses Haraka". Matt Sergeant. Retrieved 15 February 2015. 
  9. ^ "About, Thanks". Craigslist. Retrieved 15 February 2015. 
  10. ^ "SMTP Haraka". Mail Toaster 6. tnpi.net. Retrieved 15 February 2015. 
  11. ^ "auth_ldap". Haraka. Retrieved 15 February 2015. 
  12. ^ "auth_vpopmaild". Haraka. Retrieved 15 February 2015. 
  13. ^ "access". Haraka. Retrieved 15 February 2015.