How to install an extension

October 13, 2006

One of the coolest parts about Thunderbird (and it’s brother Firefox) is the ability to install extensions, which allow them to add some new feature or function.  Here’s the blurb from the Mozilla website:

Extensions are small add-ons that add new functionality to Mozilla applications such as Firefox and Thunderbird. They can add anything from a toolbar button to a completely new feature. They allow the application to be customized to fit the personal needs of each user if they need additional features, while keeping the applications small to download.

Extensions Page

As an example, we are going to install Lightning, which is the calendar extension for Thunderbird. Here’s what you need to do:

  • Open a web browser.
  • Go to This is the official page from Mozilla (the organization responsible for Thunderbird) for Thunderbird extensions.
  • Click on the Extensions tab.
  • Type Lightning into the search field at the top of the page and hit Enter.
  • When the search results come back, Lightning should be the first option. Click on the name of the extension and it will take you to the info & download page.
  • This set of instructions varies a little, depending on what operating system you use:
    • Mac: Hold down Control and then click on the “Install Now for Mac” link in the green box. Save the file on your desktop.
    • Windows: Right-click on the “Install now for Windows” link in the green box and save the file on your desktop.
  • Now open Thunderbird and go to Tools > Extensions.
  • Click the “Install” button.
  • Find the file you downloaded earlier onto your desktop and click “Open”.Installing an extension
  • This will bring up a little dialog window and will begin a count-down sequence on one of the buttons at the bottom. When the count-down finishes, the button will say “Install”. Click that button and the extension will install and take you back to the Extensions Manager.
  • You will need to restart Thunderbird in order for the extension to work, so close Thunderbird, and open it again.

And there you go. You should have a calendar at the bottom left of the Thunderbird window. As for using it, that’s another article, but the process above will work with any extension you want to install in Thunderbird. Personally, I recommend Lightning and Morecols. Morecols gives Thunderbird the ability to import & export contacts using the vCard format. You can find that extension here.