tested with: thunderbird 68.6.0 (64-bit) on GNU Linux Debian 10

if one uses the build in calendar of thunderbird (it was called sunbird, was replaced by lightning)

go into advanced config editor: (about:config)



and double-click on the entry

to change it to false


then simply close thunderbird and restart it


About Your Rights

Mozilla Thunderbird is free and open source software, built by a community of thousands from all over the world.

There are a few things you should know:

  • Thunderbird is made available to you under the terms of the Mozilla Public License.
    • This means you may use, copy and distribute Thunderbird to others.
    • You are also welcome to modify the source code of Thunderbird as you want to meet your needs.
    • The Mozilla Public License also gives you the right to distribute your modified versions.
    • You are not granted any trademark rights or licenses to the trademarks of the Mozilla Foundation or any party, including without limitation the Thunderbird name or logo.
    • Additional information on trademarks may be found here.
      Some features in Thunderbird, such as the Crash Reporter, give you the option to provide feedback to Mozilla.
    • By choosing to submit feedback, you give Mozilla permission to use the feedback to improve its products, to publish the feedback on its websites, and to distribute the feedback.
    • How we use your personal information and feedback submitted to Mozilla through Thunderbird is described in the Thunderbird Privacy Policy.
    • Some Thunderbird features make use of web-based information services, however, we cannot guarantee they are 100% accurate or error-free.
    • More details, including information on how to disable the features that use these services, can be found in the service terms.
    • In order to play back certain types of video content, Thunderbird downloads certain content decryption modules from third parties.



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