Exchange EWS Provider Add-on for Lightning (Thunderbird/Seamonkey)

(2014-10-21) As you can read I no longer maintain this add-on. But the guys from Ericsson have taken over maintanance. You can get new versions from their github page: https://github.com/Ericsson/exchangecalendar/releases.

I will keep my pages online for the archive.

(2014-05-08) I do not maintain this add-on anymore. Anyone who would like to take over can use the source at Github for it’s own fork. Thanks to everyone who has supported and helped to get the add-on to it’s current state.

!!! The next information is old and outdated !!!

lightningexchangecalendarWelcome on the website with the only add-on for Thunderbird and Seamonkey which will add access to you Exchange calendars, contacts and Global Address List (GAL). It is an add-on for the Lightning Calendering Add-on and will allow you to communicate with an Exchange 2007, 2010 and 2013 server using the Exchange Web Service (EWS) interface.You can access any Calendar, Task or Contacts folder on the EWS server in an easy way. And also manage your “Out of Office” settings.


  • Version 3.2.x for Thunderbird 12 up to 27 (tested up to and with 27).
  • Version 3.1.x for Thunderbird 6 up to 17 (tested up to and with 17).
  • Version 3.0.x for Thunderbird 6 up to 17 (tested up to and with 17).
  • Version 2.x.x for Thunderbird 6 up to 14 (tested up to and with 14).
  • Seamonkey 2.6.1 – 2.20.
  • Lightning add-on
  • This add-on.
  • Access to an Exchange Webservice Server (EWS) with an username, password and/or primarySMTP or email alias.
  • The Exchange Webservice Server of Exchange 2007, 2010 or 2013. Or that from Microsoft Office 365 (see FAQ for howto).

The latest stable version (3.1.3 released 25th of October 2012), which can be newer than on the Mozilla repository, can also be downloaded from this site: [download id=”13″]. If you find problems please report them to the bugzilla. What has changed please see [download id=”14″].

The latest development version (3.2.x) can be downloaded through this link: [download id=”17″]. Because of it’s development nature some new functionality might only work half because it is still in development. Or it is a bug fix which is still in it’s testing phase. If you find problems please report them. See Reporting Bugs. What has changed please see [download id=”18″]. (On GitHUB this is the “master” branch).
Please try this version and turn on offline cache (below calendar settings). When you already use offline cache please turn it first off for the calendar. Restart TB and then turn it on again. It should stay in sync now.

All versions can be downloaded from the download page.

Changed in version 3.2.0-BetaX:

  • Completely new Event Interface. We now use our own which is an extension of the one default in Lightning.
  • New TimeZone function for matching between the Exchange TimeZone and the Lightning TimeZone.
  • Almost complete rewrite of task/todo handling.
  • It will now try to show the Exchange time zone for the start and end times as close as it can match it to the one in Lightning.
  • Added the Exchange SOAP Autodiscovery functionality. This will be used first and when it fails it will fall back to the old POX Autodiscovery.
  • Can follow redirectAddr response from Exchange.
  • Will try Basic authentication as default when available.
  • Fixed problems with opening attachments when having multiple items open.
  • Adjusted reminder configuration to what is possible in Exchange.
  • Address autocompletion for composing emails or adding attendees to calendar event.
  • Showing of icon/image for contact in address book.
  • Added Exchange Task details.
  • Fixed editing Out Of Office messages with HTML editor.
  • New Exchange server version detection.
  • Rich text description editing/viewing including link editing and following.

What can it do:

  • Support Exchange server 2007, 2010 and 2013 (Office365).
  • Sync Calendar, Task/Todo and Contact items from an EWS (Exchange) server.  Syncing is done on a user settable poll interval. It will track changes on the server and update the local memory cache.
  • Create, modify and delete calendar events and task/todo items. They will get synced immediately with the EWS server.
  • Contacts are currently read-only.
  • Search the Global Address List (GAL).
  • Use contacts and GAL in address auto completion.
  • During creation of a new calendar you can use the Exchange Autodiscover functionality (when enabled on the Exchange server) to find the right server and mailbox settings. Selecting the right folder is easy with the build-in folder browser.
  • You can access any Calendar, Task or Contacts folder on your EWS server as long as you have the right primarySMTP or alias email address and enough permissions for the used user.
  • Let it poll your inbox for meeting invitation request or cancellations. They will show up in your calendar.
  • Manage how meeting invitations or cancellations are automatically handled (responded to).
  • Add as many calendar objects as you wish and Lightning will allow.
  • Manage “Out of Office”settings for each calendar mailbox.
  • Import ICS files.
  • Export to ICS files. (Experimental: new since 1.8.0a4 not a full calendar yet only local memory cache)
  • Manage and view attachments.
  • Edit event/todo description with rich-text. Colours, fonts, links, etc…
  • User availability (Free/Busy) information.
  • Currently in Dutch (Nederlands), English, French (Français) (Thanks to Dominique Fillon) , Swedish, Japanese and German (Deutsch) (Thanks to Christian A. Meyer) localizations. When you would like to make a translation for your language please let me know .
  • Can work with Basic, Negotiate and Kerberos authentication. Please see this page for an explanation. No NTLMv1 or NTLMv2 on Linux.

Known issues:

  • When Thunderbird is started or a new Calendar is added it can take some time to load and cache the items from the EWS server. Be patient it will all be loaded. After it is loaded it is fast because it will work with an local temporary memorycache.
  • Because of the previous slowness. When you try to change, add or delete an item during loading this change might take some time to be synced to the EWS server.
  • And those mentioned in the bugzilla.
  • It is not possible to accept or decline assigned tasks. Microsoft does not provide the necessary API calls for this. Even OWA cannot do this. Only outlook.

For questions please send them to Ericsson but first read the FAQ section or have a look at the Forum pages.

If you think of a nice feature or functionality which currently is not available have a look at the feature request page.

If you find a bug in this add-on please report it at https://www.1st-setup.nl/bugzilla/.

319 Responses to Exchange EWS Provider Add-on for Lightning (Thunderbird/Seamonkey)

  1. Denis says:


    Is there any version compatible with thunderbird 17 ?

    kind regards,

  2. fizze says:

    Version 3.1.3 also works in Thunderbird 17.
    Although the update wizard removed the plugin (and it’s settings) for me!

    After I added it manually again it worked.

  3. Denis says:


    Second idea : do you have an idea to make a downgrade to version 16 ?

    Kind regards,

  4. Fritz says:


    i`ve downloaded the Version 3.1.3 but the installation end with an error.
    This Version is not compatible with Thunderbird 17.

    Pleas help.

  5. pabouk says:

    I am currently using the version 3.1.3 with Thunderbird 17.0 on Ubuntu 12.04.1. It works without problems.

  6. JohnW says:

    Just dowloaded latest version of this add-on for use with Thunderbird 17.0 and Lightning 1.9.

    Trying to add an Office 365 calendar …
    > autodiscovery doesn’t work
    > if I use the ‘manual entry’ instructions in FAQs, all seems to go well until I get to step 10 “Click the “check….” button. When it asks your password and username fill in the password and check the remember checkbox.”
    … when I do this I just continuously get prompted to re-enter my username & password (I’m definitely using the right password btw).

    any suggestions?

    • JohnW says:

      Solved it!!!! 🙂

      Took the hint from Bernhard’s November 19th post above … if you install ExQuilla for Microsoft Exchange add-on first, you can use the auto-discover in ExQuilla to find the name of your Office365 server url (which btw is different than the url that Office365 tells me!).

      Then … once you have the correct url for your Office365 server, just use your standard Office365 email account name, do not add ‘.onmicrosoft.com’


  7. Martin says:

    Is there any special reason why the plugin version on mozillas homepage is very old and not updates anymore?
    I think it’s a great addon by the way.

  8. Ton says:

    Hi Michel,
    Version 3.1.3 works for me on Thunderbird 17.0 with Lightning 1.9 on Windows.
    3.1.201 did not.
    Very cool add-on, keep up the good work!

  9. Peter says:

    Great add-on.
    One remark, when I add an all-day event outlook-users see it from 1:00 am to 1:00am the next day

  10. Elwin Savelsbergh says:

    Great add-on. This is the essential feature for using Thunderbird at work! However, when I got back after Christmas, it suddenly stopped working , both at the office computer and at home. My google agenda’s are still there, but the Outlook agenda does not load (keeps asking for login).
    I am using TB 1.7, Lighting 1.9 and Exchange plugin 3.1.3. I saved the communications log, no idea how to interpret that, but I could send it if you let me know an email address. Any idea what could be wrong?

    • admin says:

      Did they, your system admins, change something in the authentication mechanism for the Exchange server?

      • Elwin Savelsbergh says:

        Probably, who knows? ‘They’ are pretty remote in a University organisation with centralized Exchange servers. Other forms of access (e.g. ipad) still work.

  11. Thijs says:

    Your work for this addon is greatly appreciated, in fact its the only thing making thunderbird a real alternative to outlook when working in (“hostile”) exchange environments.
    There is however one feature missing that you might not have thought about yet:
    In many organizations we work with group mailboxes which are normal mailboxes on which your username has rights to access it using your credentials. In exchange webmail you can view them by changing the webmail url to include email address for the secondary mailbox. In imap you can view them by adding its login name after your own (myusername@domain/usernamemailbox).
    In your addon however I can’t get this to work. It works when I add the calendar after I’ve added my own calendar (it then probably uses existing connection?), but after I restart thunderbird it now asks credentials and they never work.
    Could you look at a sollution for adding secondary EWS calendar’s using different credentials than the calendar’s mailbox?
    The only alternative is to give the password for this mailbox around, but thats not really great with administration and security 😉


  12. Amélie says:

    The latest version of the add-on seems not to be compatible with Thunderbird 17.0.3, when is a compatible version to be expected?

    • admin says:

      I have the latest version 3.2.0-beta working with 17.0.4 and i am currently testing in thunderbird 20 (Beta channel of Mozilla)

  13. Pingback: Connecting Thunderbird to an Exchange Calendar

  14. Niko says:

    Hi, after using your extension for several months, somehow my profile got broken (I suspect an issue with the offline mode, but that’s not my concern here). I can’t connect to any of my Exchange calendars anymore, I will always receive a 401 error (“unauthorized”).
    Tried many things, installed the latest 3.2.0 beta, tried to uninstall your extension and lightning itself, cleaning my profile, I even created a fresh profile and used git to track the configuration changes when adding an exchange calendar and then deleted the relevant files in my old profile – nothing worked, when adding a new calendar just the above error is shown, no password is requested from me. As mentioned, creating a fresh profile and adding a calendar works fine, the password dialog shows up as expected (which it doesn’t in my old profile).
    TB version is 17.0.4. Could you give me any hint what part of my profile prevents the correct (re-)authentication?

    Thanks a lot!

    • admin says:

      Are you using Linux or Windows? On Linux NTLMv2 authentication does not work and it could be the Exchange administrators changed authentication to NTLMv2.
      Please try latest Beta version.

  15. Niko says:

    I alreay tried the latest beta, as previously posted. Anyway, how would this explain that it works when I create a new TB profile, but it doesn’t work with my existing one anymore?

  16. Amélie says:

    Unfortunately when I try to install the version 3.2.0-beta I get the message: “Exchange 2007/2010 Calendar and Tasks Provider could not be installed because it is not compatible with Thunderbird 17.0.5”

    • admin says:

      Are you installing it in Firefox or Thunderbird. I have it currently installed in Thunderbird 17.0.5
      For installation in Firefox right click on the link and then select “Save link as”. In Thunderbird goto the add-on page and use “install add-on from file”.
      This should work. Do not left button click on the link in Firefox because firefox will install the add-on in it self and not in Thunderbird.

      • Amélie says:

        OK I understand now. When I clicked on the link it tried to install the plugin in Firefox. I downloaded the plugin and installed it from the file in Thunderbird, now it works. Thanks for your help.

  17. Richard Cain says:

    Finally, I’ve got it working. The main issue was that the version in the Thunderbird repository is still 1.xx – Is there any way to get them to stock the latest version?

    • admin says:

      It is true but as the latest version has an auto update functionality included Mozilla does not accept/allow it any more. It violates their policy.
      I included the automatic update functionality as Mozilla will review each change and a review can take up to three or four weeks. In that time I sometimes released one or two new versions to fix problems.
      I will see if I can post a new version to the Mozilla repository without the update functionality and hope they will accept it.

  18. Pingback: Almost a new version (3.2.0) | 1st Setup

  19. Joerg says:


    I am testing Dev. .2.0-Beta20 (30).
    After adding the Server URL, postbox, user and domain name and testing account I get:

    Fehler bei der Abfrage des Servers und des Postfachs:HTTP Client error 405: Method not allowed

    405 – HTTP verb used to access this page is not allowe

    (Code: -19)

    With previous version I did not had this problem. Habe you hints how to dig further into this problem?

  20. paul mitchell says:

    I am using Thunderbird 17.04, Lightning 1.9.1 and EWS 3.2.0-Beta24. I can install with no errors and connect to my calendar in Office 365, perfect.
    After adding an Exchange contact folder under Exchange contacts in the address book, both mail and calendar have access to the GAL. I can’t see the list, but when I start typing a member’s name, the system suggests names from the GAL.
    The only outstanding item is personal contacts. Do you know how I can access my contacts that are stored in Office 365 via Thunderbird?

  21. John Lancaster says:

    In the Thundirbird Options -> Exchange (EWS) window on the Others tab what do Communications Preferences and HTTP usre agent do?

  22. Stephen Miller says:

    Can I have one profile that points to both my calendar and my tasks? Or do I have to have two profiles? One that points to my Calendar and one for my Tasks? Thanks.

  23. Deepak Dasgupta says:

    Thank you for this.
    I have the Beta 28 installed in TB 17.0.6. Some issues I find

    1. The Email in properties of calendar is not showing the configured email address
    2. Probably due to point 1 above, after accepting the invitation does not delete from inbox
    3. Sometimes the Accept/decline/Tentative option do not show up and only Open shows up. then I have to Open the invitation and select “I will attend” from there and then delete the invitation from inbox
    4. quite high cpu usage for thunderbird. I am using Fedora 18

    Thank you and BR, Deepak

  24. schmidi says:

    Hi, thanks for this greates Plugin. I´m used the Version 3.1.3 but i has the Problem to sync the Kategorie with the Exchange 2010. I don´t no what is the Problem. Can you help me? Thanks for your Service or Feedback.

  25. Kyle says:

    I was wondering what the “(r/w jobs)” with the syncing icon is doing in the lower right hand corner of thunderbird. I have left my thunderbird open for 48 hours straight now and the “w” number just keeps getting bigger and the sync icon never stops syncing. Am I doing something wrong?

    • admin says:

      Sorry for the late reply. The r/w stand for running and waiting jobs. In the last beta version this has been changed to “# running & # queued jobs”

  26. Brag says:

    When I try to create new event and the calendar sets to read-only mode. But I can delete the existing events.

  27. Gary Day says:


    Love this plug-in, any chance you could work on this to somehow incorporate
    a “join now” function for webex; scan through the calendar invite and if you see a webex invite then basically add an icon or make the hyperlink in the invite clickable…



  28. Russell Maclean says:

    Using the exact methods specified and once I have reached the point where I can click “Check Server and Mailbox” I click it and it simply becomes greyed out.

    Interestingly using evolution’s EWS addon I get the exact same effect, An unresponsive timeout when trying to connect to the calendar. Obviously I can reach the servers (see below)

    [root@rutherfordium log]# curl -i https://pod51021.outlook.com/ews/exchange.asmx
    HTTP/1.1 401 Unauthorized
    Server: Microsoft-IIS/7.5
    RequestId: 4454aba8-57f4-4eec-8be2-e6488c8ef4cf
    Set-Cookie: exchangecookie=6a71bfa1b3b44a76a5433ea1e1618f63; expires=Sat, 05-Jul-2014 08:12:29 GMT; path=/; HttpOnly
    X-Powered-By: ASP.NET
    X-DiagInfo: HKXPRD0310CA010
    WWW-Authenticate: Basic Realm=””
    Date: Fri, 05 Jul 2013 08:12:28 GMT
    Content-Length: 0

    • Michael says:

      I too am experiencing this issue, neither the auto-discovery or manual entry works. Simply sits there after clicking “Check Server…”

  29. Russell Maclean says:

    Navigating to the above URL I can login, However not with the recommended user@domain.onmicrosoft.com , but rather user@realdomain.net.au works and my browser GET’s the xml.

  30. Russell Maclean says:

    While the above is happening, Thunderbird is hammering CPU. Stracing thunderbird reveals ‘Resource tempoaryily unavailable’ being constantly spammed. (Sorry for multiple posts but thought this might help)

  31. Deepak Dasgupta says:


    After upgrading to Fedora 19, seems like the jobs hang causing massive /var/log/messages file. This is happening in the latest beta version. I have now moved to the stable version so I will inform how it goes.

    BR, Deepak

  32. Prabhu Gopal says:

    I am also get stuck here, during config with thunderbird-lightning-microsoft exchange 2007/2010. As Russell Maclean, the “Check server and mailbox” button get greyed out and no response further.

  33. Bruce says:

    Running the latest Beta version. Working much better than the stable against our Exchange 2010 servers. Would be nice if URL’s in the description field of an event were clickable.

  34. Vadim P. says:

    Having some difficulty setting up a new Calendar. When the autodiscovery fails, I get about 3 pop-ups with the “Error during autodiscovery: Ready state != 4, readyState:0 (-100)” error – this is using 3.2.0 beta.

    Trying the internal domain name previously used to pop up 2 untrusted certificate errors – but it did not allow me to accept either of them, so I had to cancel. Now, for some reason autodiscovery just waits and nothing happens.

    I’ve successfully setup ExQuilla for the mail, but this has been difficult.

  35. Mohit k says:

    Dear Admin/ Member,

    Please help me to download below extension

    – Thunderbird Extension – Exchange 2007/2010 Calendar and Tasks Provider 1.8.5 (Version 1.8.5).

    I have tried from mozilla site but unable to find the page even received “Page not found” for any version.

    It will be highly appriciated and thankful to all to help me.

    Best regards,

  36. Dylan says:

    I’ve installed the new exchangecalendar-3.2.0-Beta46 with Thunderbird 17.0.8 and it tells me when I hover over the icon on my calendar that “The calendar Work is connected to the exchange server.” The problem is, it doesn’t matter how many times I synchronize my calendar, nothing ever appears. This is really detrimental for me as Evolution isn’t a mail client that I can use (it’s not as detailed as I need it to be – I.E., it refuses to accept my HTML signature and locks up), but the calendar just works.

    Is there anything that I can send to you – or anything you can think of that I need to do to pull my calendar down – so that I can get this issue resolved as quickly as possible?

    Thanks and V/R,
    Dylan Wooten

    P.S. My office just migrated over to the new 2013 series of Office (to include Exchange 2013).

  37. Darrell says:

    This is unbelievable! No wonder people get fed up with open source software. You find a great piece of software or addon, and after a year or so of great progress and promising features, the author comes in and says, “Sorry folks, I don’t have any more time to work on this.” Then it gets set on the shelf to collect dust and eventually be obsolete. This was a good one, and I hate to see it go. Thanks for all the work.

  38. Tim Urberg says:

    This plugin has been taken in by Mesquilla and hopefully the’ll keep it up to date.


  39. Darrell, I don’t see what your complaint has to do with free or open source software. Proprietary programs get suddenly discontinued all the time too; at least with free software you and everyone else has the option of taking over the project.

    Thanks to 1st Setup for all their hard work on the project so far. I hope they find time to resume development; if not, perhaps the download link can be restored so that the project doesn’t get completely lost.

  40. Olivier says:

    Thanks a lot for bringing the addon back to life, even if the pace of development has slown down 🙂

  41. Diego says:

    Had to get back to 3.2.0-beta46 as beta 49 permanently turned my calendar to read-only.
    Server: Exchange2007_SP1 (

  42. Kirurgs says:

    Thanks for addon, but currently I can’t use it, as I can’t link it to my emails, e-mail list shows only “None”.

    Ubuntu 13.10, exchange 2007_SP1 (, TB 24.1, Addon Beta52 (problem was even before beta 49), maybe related to TB24.1.

  43. Kirurgs says:

    Thanks, Beta56 works, no problems with linking now.

  44. Bernadette says:

    thank you for this! Beta 56 works great. LinuxMint 15, Thunderbird 24.1, Exchange Server 2010!!

  45. Bruce says:

    When I delete a single occurrence of a repeating event, it sometimes remains in my Lightning calendar even though it is gone from my EWS calendar. If I try to remove it from the Lightning calendar again, I get an error, presumably because it doesn’t exist in the EWS calendar. It’s annoying because reminders for the event continually pop up and there is no way to dismiss them because the event does not exist in the EWS calendar. Using beta56.

    • admin says:

      This is a know bug. which is currently solved in the latest github version. I am still doing some test but hope to release this as a beta this weekend.

  46. Tiago says:

    Thunderbird and Lightning appear to be moving targets… A Thunderbird version upgrade has a strong chance of breaking Lightning, which in turn has a strong chance of breaking Exchange EWS Provider.

    And this happened again today. Thunderbird (on Linux) was upgraded to 24.1.1 which broke Lightnning 2.6.2 and therefore Exchange EWS Provider. I fixed Lightning by upgrading it to 2.6.3. But Exchange EWS Provider is still not working..

    This is frustrating. And I’m not necessarily blaming Exchange EWS Provider’s developer. He’s at the end of the chain. I just think there’s something wrong in the Thunderbird project when new versions bring incompatibilities with existing add-ons on a regular basis!

  47. Paul Mitchell says:

    I know that you are developing your add-on independently of Exquilla, but do you know if your latest beta version suffers from the same problem as the Exquilla version?
    3 or more daily recurring events to cause unacceptable performance issues in memory usage, CPU usage, and locking of the user interface.

  48. Frank says:

    I thought this project was going away permanently – so happy to see that you’re able to continue work. I have used DAVmail in the interim, and it is so painfully slow. I just downloaded beta61, installed it, and everything seems to be working great – and really fast!
    Fedora 19 x86_64, Thunderbird 24.1.0, Lightning 2.6.2 (both from Fedora repository)

    • Frank says:

      I guess I posted too soon – Calendar and Address Book work great as I mentioned. However, if I attempt to create a task (cloned the working calendar, then changed the “Folder Base” to “Tasks folder”), I can enter all the information, but “Save” or “Save and Close” do nothing.

  49. Steve Wallcave says:

    3.2.0-Beta24 does not have any performance issues for me with multiple recurring events. All versions after it cause me performance problems. I have been happily using Beta24, Lightning 2.6.3, Thunderbird 24.1.1 on Windows 7.

  50. Brendon says:


    Exchange EWS Provider Add-on: 3.2.0-Beta61 and then 3.2.0-Beta62
    Lightning: 2.6.3
    Thunderbird: 24.1.1
    OS: MacOS 10.8.5

    After installing 3.2.0-Beta61 and then 3.2.0-Beta62, I’ve noticed that when I open an event/meeting invite in nearly every one the Description field is now blank. If I hover over the event/meeting invite in the Today pane, the text in the Description field is displayed.

    I have cleared the Exchange cache a few times and also deleted and recreated the calendar once, however the problem persists.

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