⚠️ This project is no longer maintained.

ElasticInbox is an open-source, reliable, distributed, scalable email store.

The goal of this project is to provide a highly available email store without a single point of failure that can run on commodity hardware and scale linearly. ElasticInbox can easily scale to millions of mailboxes, with hundreds of thousands of messages in each mailbox.

To achieve this, ElasticInbox relies on proven technologies:

  • Apache Cassandra for metadata
  • Cloud object (blob) store for messages. ElasticInbox supports all major private and public object stores like AWS S3 and OpenStack Object Store through the Jclouds library.

Next steps

News

  • 22 Sep 2013 — Version 0.4.0 released.
  • 06 Dec 2011 — Initial version (0.2.0-SNAPSHOT) pushed to Github.

License

ElasticInbox is an open-source project distributed under BSD license.

Elastic

The message read and write throughput scales linearly as more nodes are added.

Underlying components - Cassandra and Blob Stores also can scale linearly to thousands of nodes.

Decentralized

ElasticInbox itself was designed with "share-nothing" architecture in mind where every node is independent. This means no single point of failure.

Cassandra and Blob Stores are also decentralized.

Fault-Tolerant

ElasticInbox stores information in Cassandra and Blob stores. Both technologies provide automatic replication to multiple nodes. Both support replication across multiple data centres. Failed nodes, whether it's ElasticInbox, Cassandra or Blob store, can be replaced with no downtime.

Architecture

The diagram below depicts high-level architecture:

ElasticInbox Architecture

Why ElasticInbox?

The typical email delivery process involves several components:

  • Mail User Agent (MUA) - e.g. Mozilla Thunderbird, Microsoft Outlook
  • Mail Transfer Agent (MTA) - e.g. Postfix, Exim
  • Mail Delivery Agent (MDA) - ElasticInbox
  • IMAP, POP3, and other interfaces to access mail

MDA is responsible for storing messages. Most of the existing MDAs (or sometimes MTAs) store messages only on the locally mounted filesystem which is sufficient when you have a few thousands of accounts. However, when you need to serve millions of accounts, a local filesystem is not an option.

Solution

ElasticInbox MDA can serve millions of accounts and scale linearly - no bottlenecks, no single point of failure. Multiple replicas provide fault tolerance. This is a perfect solution for the cloud environment - just add more nodes as you grow. Messages are delivered over the standard LMTP protocol.

In addition to MDA, ElasticInbox also supports RESTful APIs for managing, retrieving and storing messages. It provides an easy way for building web services (such as webmail, admin panel, etc.) on top of ElasticInbox.

POP3 is supported for mailbox access and we also plan to add support for IMAP. See the roadmap for the full list of planned features.

Internals

APIs

Operations

  • Installation (coming soon)
  • Configuration (coming soon)
  • Monitoring

Roadmap

  • Native support for message threads
  • Built-in filtering engine based on SIEVE protocol
  • Built-in search engine
  • IMAP support

Binary Package

Latest version is 0.4.0-SNAPSHOT (beta quality, although used in production):

Requirements

Getting Source

The source code is available on GitHub. Fork, make your changes and contribute. We accept pull requests.

To build and run from the source you will need Maven 3 and Git: 

% git clone git://github.com/elasticinbox/elasticinbox.git elasticinbox
% cd elasticinbox
% mvn clean install pax:provision -DskipITs

Mailing List

If you have questions regarding ElasticInbox functionality, configuration or operation, join the user mail list:

Stay Updated

Stay in touch, follow us on twitter and github:

@elasticinbox   •   github