Wild Duck Mail Agent

This is a very early preview of an IMAP server built with Node.js and MongoDB.

Goals of the Project

Build a scalable IMAP server that uses clustered database instead of single machine file system as mail store
Push notifications. Your application (eg. a webmail client) should be able to request changes (new and deleted messages, flag changes) to be pushed to client instead of using IMAP to fetch stuff from the server

Todo

Does it work? Yes, it does. You can run the server and get a working IMAP server for mail store, LMTP server for pushing messages to the mail store and HTTP API server to create new users. All handled by Node.js and MongoDB, no additional dependencies needed.

Is the server scalable? Not yet. These are some actions that must be done:

Separate attachments from indexed mime tree and store these to GridFS. Currently entire message is loaded whenever a FETCH or SEARCH call is made (unless body needs not to be touched, for example if only FLAGs are checked). This also means that the message size is currently limited. MongoDB database records are capped at 16MB and this should contain also the metadata for the message.
Optimize SEARCH queries to use MongoDB queries. Currently only simple stuff (flag, internaldate, not flag, modseq) is included in query and more complex comparisons are handled by the application but this means that too much data must be loaded from database (unless it is a very simple query like "SEARCH UNSEEN" that is already optimized)
Optimize FETCH queries to load only partial data for BODY subparts
Build a publish-subscribe solution to notify changes process-wide (and server-wide). Currently update notifications are propagated only inside the same process (journaled update data is available from DB for everybody but the notification that there is new data is not propagated outside current process).
Parse incoming message into the mime tree as a stream. Currently the entire message is buffered in memory before being parsed.

Usage

Install dependencies

npm install --production

Modify config file

Run the index queries in MongoDB (optional, the app would work without it as indexes only become relevant once you have more than few messages stored)

Run the server

npm start

Create user

Users can be created with HTTP requests

POST /user/create

Arguments

username is an email address of the user
password is the password for the user

Example

curl -XPOST "http://localhost:8080/user/create" -H 'content-type: application/json' -d '{
    "username": "username@example.com",
    "password": "secretpass"
}'

The response for successful operation should look like this:

{
    "success": true,
    "id": "58bd6815dddb5ac5063d3590",
    "username": "username@example.com"
}

After you have created an user you can use these credentials to log in to the IMAP server. Additionally the LMTP server starts accepting mail for this email address.

License

Wild Duck Mail Agent is licensed under the European Union Public License 1.1.

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