Exchange 2007/2010/2013 Calendar, Tasks, Contacts and GAL Provider.
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advancingu Merge pull request #170 from sergio-mena/ec-4.0
Fixed usage of addDuration (which returns void)
Latest commit e30ee34 Apr 7, 2018


Exchange Calendar is an add-on for Thunderbird and Seamonkey.

It extends the Lightning add-on to provide Microsoft Exchange support.

Exchange Calendar extension can:

  • Synchronize calendars, tasks, and contacts with a Microsoft Exchange server.
  • Create, edit and update events and tasks.
  • Display contacts from your address books and the global address list (they are only readable, they are usable with address autocompletion).
  • Manage the Exchange « out of office » feature.

This extension requires:

  • Lightning extension corresponding to the Thunderbird release.
  • The Exchange server has to provide an Exchange Web Service.

This extension was developed by its original author (Michel Verbraak) for Exchange 2007, 2010 and 2013.

The ExchangeCalendar community is now maintaining this extension. Support is best effort and cannot be guaranteed. Contributions are welcome.


This add-on is open source and based on the work of many contributors.

This project is a community driven effort to develop and maintain the "Exchange EWS Provider" extension originally created by Michel Verbraak.

Provide feedback, report issue

You are welcome to provide feedback on our Github project:

Please note that the project is built only for latest stable Thunderbird release and latest stable Lightning release.

The more information you can provide about an issue, the easier it becomes to reproduce and fix. Examples of helpful informations are:

  • Thunderbird version
  • Lightning version
  • Active Thunderbird add-ons
  • Log output

Get project and build it

To build the add-on, you have to:

# clone this project
git clone
cd exchangecalendar
# build it
make build

Then an xpi file is created in the project folder. This file is directly installable from the add-on page of Thunderbird.

If it doesn't work, please check you have these tools installed (example for Debian):

sudo apt install git-core zip

Patch the code

To help us to maintain the code, we will be thankful to follow these main guidelines:

  • Use indentation with 4 spaces
  • Avoid too long lines, try to break long lines into smaller ones
  • Avoid to write "spaghetti" code with too many if/else imbrications
  • Try to keep code simple to help us maintain it on long term

Note that our Makefile has a beautify target which will try to beautify all JavaScript (requires jsbeautifier Debian package) and XML code (requires tidy package) to help maintain a clean code.

When your patches are ready, you are welcome to do pull requests on our repository.

Please help us to review your code by making multiple small pull requests instead of big ones modifying big parts of the code.


You are welcome to provide translation updates on our Transifex project:


This software is provided on a best-effort basis without any warranty. Please see the license for details.

Some of the icons and images used are from the Fugue Icons Collection made by Yusuke Kamiyamane.