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E-mail libraries for the gaia e-mail client. A bunch of node and AMD modules get r.js optimized into a single JS file that gets loaded into the Gaia email client. The library can also potentially be used for other clients too, as long as you are cool with our design decisions.

Design Decisions

We are targeting B2G phone devices where resources are relatively precious. We:

  • Optimize for only synchronizing a subset of (recent) messages in each folder.
  • Try and cache as much as possible for latency and network utilization reasons.
  • Present messages to the UI as part of a "view slice" where the UI asks for the most recent set of messages for a folder and we provide that in a slice. If the users wants to scroll further back in time, the UI asks the backend for more messages which may in turn trigger the synchronization logic as needed. The takeaway is that the UI is presented with a stream as opposed to some random access database that contains the fully replicated state of the entire IMAP folder.
  • Use IndexedDB for storage, optimizing for Firefox's specific SQLite-backed implementation that uses 32K pages with snappy compression on a per-value basis.
  • Support the UI running in a separate thread/JS context from the back-end with only JSON or structured-clone communication possible between the two.
  • Are targeting Yahoo and GMail IMAP for good support which means we need to work on relatively bare-bones IMAP implementations. For example, Yahoo does not support IDLE and GMail barely supports it. Neither support CONDSTORE or QRESYNC, etc.

What Works / Will Work

We have working IMAP and ActiveSync implementations. There are some current limitations that we are working to resolve, such as message moves and auto-configuration.

All bug tracking happens on under the "Boot2Gecko" product and the "Gaia::E-Mail" component.

Find more links from the wiki page at:

New Code

This repo provides:

  • "Client daemon" logic that is the backend. It does the IMAP protocol talking, storage maintenance, etc. It communicates over a JSON bridge with the front-end which provides the:
  • MailAPI, for use by the UI/front-end. It communicates asynchronously with the back-end over the JSON bridge.

Currently, the client daemon and the MailAPI live in the same page and we are not round-tripping the data through JSON because it would needlessly create garbage and slow things down. But the idea is that the client daemon can live in a background page or a (sufficiently powerful) worker, etc.

Code Reuse

We are aggressively attempting to use existing JS libraries. Currently, these are mainly node libraries. We use a combination of slightly-forked versions, shims, and AMD-wrappings (using volo) to get this to work. We use MIT-licensed code from the following projects or converted projects:

We shim the following ourselves to the minimum required:

  • node's Buffer implementation
  • node's crypto module, for crypto.createHash('md5") to support hash.update and hash.digest("hex").

We fork the following:

  • node-imap from This was done because we were trying to avoid shimming the node network API in favor of using our TCP WebAPI. Changes were also required because of the differences between node's Buffers and our Buffer-shim based on typed arrays. Our fork is currently intended to be a bit of a dead-end. Since node is abandoning Buffers in favor of typed arrays/data-views, we will likely migrate to a new upstream revision of this library or an entirely different library in the future. (Our current major concern for IMAP is on pipelining requests, so whatever library best offers that is likely what we will end up using. If no other library offers it and node-imap is willing to accept patches for doing so, we will likely stick with node-imap.)

The "And More" bit

This repo started out life as a restartless Jetpack extension for Firefox to provide a restartless version of the TCP WebAPI with permissions. There was also an intent to provide a more desktop friendly development UI. Code for this stuff is still in here in various states of workingness, but is not a priority or goal and a lot of it has now been removed. That which remains is planned to be deleted or moved to a separate repository.


To make sure the submodules are initialized properly, please make sure to check out the repository recursively:

git clone --recursive

If you already checked out without the --recursive flag, you can try the following command inside the repository directory:

git submodule update --init --recursive

Installing Into Gaia

Make sure you have a symlink, gaia-symlink, that points at the root directory of your gaia checkout.

For example, to create it:

ln -s ~/git/gaia gaia-symlink

Then, to run all the build steps and to copy our used files across into gaia, run:

make install-into-gaia

Unit Tests

Unit tests are intended to be run in an xpcshell instance that was built as part of a b2g-desktop build, but a Firefox or Thunderbird xpcshell build should work equally well. The Makefile has the standard xpcshell-tests, check-one, and check-interactive targets. They depend on your having "b2g-srcdir-symlink" and "b2g-builddir-symlink" files in the root of your gaia-email-libs-and-more checkout so it can build the path properly.

The IMAP tests like to run against real servers. asuth uses dovecot installed on Ubuntu hooked up to postfix on localhost, but the unit tests can run against any server anywhere. For example, a somewhat recent dovecot on a remote server works just as well as localhost, it's just harder to use on a airplane. Some servers, such as Yahoo's IMAP at the current time, are too broken to use the unit tests. For example, Yahoo's APPEND command ignores the specified INTERNALDATE value, which makes it useless for many synchronization unit tests.


Create the symlinks described above for xpcshell:

ln -s /path/to/moilla-src-dir b2g-srcdir-symlink
ln -s /path/to/mozilla-obj-dir b2g-builddir-symlink

Running the Tests

To run a single test, in this case, test_imap_general.js which is located at test/unit/test_imap_general.js in the repo:

make check-one SOLO_FILE=test_imap_general.js

This will produce a log file of the run at test/unit/test_imap_general.js.log

To run all of the unit tests:

make xpcshell-tests

This will remove all existing log files prior to the run. Afterwards, all log files should be updated/exist, and a log that is the concatenation of all of the test logs should exist at test/unit/all.log

Viewing the Test Results

The logs generated by the unit tests are in JSON, but that doesn't help you much on its own. Happily, there is an HTML UI for viewing the logs, that can be found here and dubbed ArbPL which was born as a hybrid of a log viewing UI and a competitor to tinderbox pushlog that involved a server component for speed:

The easiest and most fun way to use ArbPL is to run the server. This is because the UI is able to use Socket.IO to update as new test runs come in. To be able to do this, the setup process looks generally like this:

sudo apt-get install graphviz
git clone --recursive git://
cd arbitrarypushlog/server
npm install

Things are now installed.

You can run the server by typing the following in the root of arbitrarypushlog.


The server is now running on port 8008. You can browse to http://localhost:8008/?tree=Logal and you will see the list of results. At the start of time, the database is empty, and the UI doesn't really like that, so you will need to hit refresh after you get some data in there.

To get data in, the command is:

./logalchew /path/to/test_blah_blah.js.log

Alternatively, you can create a symlink "arbpl-dir-symlink", and then use the Makefile targets "post-check-one" or "post-xpcshell-tests" to automatically run ./logalchew on the result.

To make this more obvious that this is an option for those skimming the page, this means:

make post-check-one SOLO_FILE=test_imap_general.js


make post-xpcshell-tests

Adding Tests

Because we are using xpcshell and xpcshell requires manifests to be used, if you add a new test, then you need to add it to test/unit/xpcshell.ini if you actually want it to be run.

Legal Disclaimers, Notes, Etc.

We are including ActiveSync support because it's the only sane option for Hotmail. (It also is potentially a better protocol to speak for various other e-mail services such as GMail where enabling IMAP requires user interaction and/or the IMAP mapping potentially requires special handling.)

Microsoft asserts that they have some patents on the ActiveSync protocol. If you want to use/ship/distribute this library, you are either going to want to strip out ActiveSync-touching logic or make sure that you are okay with whatever those patents are. Microsoft has some Open Source friendly words relating to some protocols, including their e-mail protocols, which may make things fine for you if you are not distributing things commercially.

Specifically, the "Interoperability Principles" program has a patent pledge:

The pledge defines that it relates to the protocols listed at:

From the "Open Protocols" page, if you click on the following links in succession, you will reach the ActiveSync documentation:

There is also a commercial licensing program known to exist:

I am not a lawyer, I am not qualified to tell you what any of the above actually mean. The above links will hopefully save you time when you or your lawyer do your research. None of this is legal advice.