Lightning 1.0 Beta 2 Release Candidate 1 is available

This time around, we had a lot less trouble then last time when preparing 1.0b2 release candidate 1. The most trouble this time was again release automation. We managed to work around the issues by producing manual builds on the same machines as our usual releases are built on.

Candidate builds for Lightning 1.0 beta2 in 32 languages are available as of now for:

A corresponding build of the Provider for Google Calendar is also available at those locations.

Note you will need Thunderbird 3.1 (or a release candidate thereof) to try it out. You are encouraged to back up your profile before upgrading. To install these builds in Thunderbird 3.1, please follow these steps:

  1. Download the build for your operating system to a folder on your hard disk.
    NOTE:Please make sure, that you right-click on the links above and choose “Save Link as…”. Otherwise Firefox will try to install Lightning and you will get an error message like “Lightning 1.0b2 could not be installed because it is not compatible with Firefox.”
  2. Open Thunderbird, then open its add-on manager via Tools –> Add-ons (or the corresponding entry in your language)
  3. Click on the “Install…” button on the lower left and navigate for the lightning.xpi file that you just downloaded.
  4. Restart Thunderbird after the add-on installation has been performed. Voila!

The candidate builds will be available for testing for up to 2 weeks. We want to release the final Lightning 1.0b2 together with Thunderbird 3.1, so we may choose to shorten this period by a few days.

Please tell us what you think of these candidate builds and file bugs in Bugzilla as you go. Thank you very much for your support, we couldn’t do it without you!

Update: Windows link fixed, thanks for the note!


  1. Hi,
    thanks a lot for this release.
    By the way, WINDOWS RELEASE LINK IS POINTING TO LINUX RELEASE ! (but everyone can get windows version by changing folder)

  2. You can also try out this version of Lightning with SeaMonkey 2.0.5. Unlike with Thunderbird, with SeaMonkey you may of course just click the link, since SeaMonkey is both a browser and a mailer. (If you install Lightning in SeaMonkey this way, you may have to enable the install by clicking “Install Software…” at the right end of the alert band just below the browser tab bar if you haven’t yet whitelisted as a source of extensions in your Preferences.)

  3. Oops… My bad. I forgot, SeaMonkey 2.0.5 is built on Gecko 1.9.1 and this build of Lightning (and Tb 3.1) are 1.9.2. If you want to test Lightning with SeaMonkey, you can, but not with this version — use an alpha “trunk build” of both.