A Closer Look at the Lightning Calendar Add-On For Thunderbird

Martin Brinkmann
Nov 9, 2011
Updated • Apr 9, 2014
Email, Thunderbird

One of the main points of criticism in regards to the email client Thunderbird was the missing calendar. While it was possible to install an early version of Lightning in previous versions of the email program, it was not really comparable in functionality with the calendar in Outlook or Google Calendar.

With the release of Thunderbird 8 came the release of Lightning 1.0. We already mentioned that in the Thunderbird release review we posted yesterday.

Lightning in terms of compatibility has made a step backwards. The calendar only supports Thunderbird 8 and later versions, which can be a serious problem for users who do not just jet want to upgrade to the new version of the desktop email client.

Mozilla has this to say about Lightning:

Lightning 1.0 is the fully integrated calendar Add-on for Thunderbird that lets users organize their schedules and life’s important events as a natural part of their email experience. Lightning gives users the ability to manage multiple calendars, create daily to do lists, invite friends and colleagues to events and meetings, and subscribe to publicly available calendars. With over a million active users, Lightning 1.0 is the calendar solution that users rely on to help them manage their daily lives at work and at home.

When you look at the release notes of Lightning 1.0 you will notice that there are not really that many notable changes to report. Most of the changes are bugfixes that resolve issues of previous Lightning versions. Lightning 1.0 has received some cosmetic changes, most notable new user interface styles for all calendar views.

lightning calendar thunderbird

When you install Lightning in Thunderbird you will notice - after a restart - that it adds a column on the right side of the program. Here you see the current date and calendar week as well as events for today, tomorrow and "soon". Lightning adds the Events and Tasks menu to the top menubar.

An import option is available supporting iCalendar and Microsoft Outlook comma separated value files. It is furthermore still possible to synchronize Lightning with Google Calendar and other remote calendar locations (via New > Calendar > On the Network).

New Lightning users should take a look at the known issues highlighted on the Lightning 1.0 release notes page.

Are you using a calendar application? If so, which?

Update: Lightning has been updated many times since it was released as a stable extension. The most recent version of Lightning is 2.6.4 which is compatible with all recent versions of the Thunderbird email client as well as SeaMonkey.

If you are new to Lightning, you may want to browse the official help topics which include guides on how to get started and configuration.


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  1. redDragon said on November 9, 2011 at 6:48 pm

    Hi I am a developer on the team, and I can tell you that the we are going to release the enterprise version of the add-on soon, and it will be compatible with Thunderbird 3.1.*

    We knew about the people hesitant to upgrade so we have delayed a number of bug fixes only for enterprise users, and wud be releasing them in a subsequent release.

  2. cyriagen said on November 9, 2011 at 5:05 pm

    Hi Martin,

    I use Lightning along with Thunderbird for years now and for my purposes it’s perfect. Nevertheless, i would like to see Sunbird being developed.
    Oh, and i can’t get familiar with Outlook Calender or Google Calender :-)

  3. DanTe said on November 9, 2011 at 4:56 pm

    Hi Martin, the sync’ing with Google Calendar caught my interest. But when I went to create a new calendar “On The Network”, it asked me for a location. Typing in [name]@gmail.com doesn’t seem to work.

    1. Martin Brinkmann said on November 9, 2011 at 5:39 pm

      DanTe, you cannot just enter your email address. You need to open Google Calendar, open Calendar Settings from the options icon in the upper right corner, switch to Calendars and click on the Calendar that you want to sync. Locate Private Address, copy XML and paste it into the location in the Thunderbird dialog. You are then asked to enter your Google Calendar credentials to complete the setup.

      1. DanTe said on November 9, 2011 at 9:33 pm

        Thanks Martin. Will try that. Maybe it’ll be a good article to teach us non-Thunderbird users how to use it.

  4. Midnight said on November 9, 2011 at 3:44 pm

    Good review, Martin and I agree with your comments.

    I’ve been using Lightning in TB since it was first released and while it does what it’s suppose to, it still lacks some functionality.

    Lightning will show Tasks and Events, as it’s suppose to, which is what I want it to do.
    In the previous versions, it would should the Events at the top of the Calendar, which it doesn’t do anymore.
    A minor flaw or setback.

    I still prefer Lightning over Outlook Calendar, but that’s my choice. :)

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