How to Install Add-on Extension:
The ideal case
In an ideal world, all the add-ons you would want are officially vetted, approved, and can be found on the official website, Addons.mozilla.org .
If you are in this category, you can simply go to the Add-ons manager tab in Thunderbird, using the toolbar entry then and enter the add-on’s name into the search box.
Once you find the add-on, click Install, then wait for it to download, then click Restart Thunderbird.
A little ideal ideal
You have given a URL for the add-on, or the add-on you want is not on the “official” page. Searched for it, as shown above, does not detect your add-on.
Go to the webpage in your browser, right-click the download link with your mouse, select “Save Link in this way”, and save the XPi file to your computer that you can find again. Download is temporarily recommended that you either use your downloads folder or your desktop.
To install a downloaded XPI file into Thunderbird you have two options.
Right-click the link and select Save or Save as shown previously.
You will be invited to download and save the file. Most browsers have a default download location, often on your desktop. Say where he downloads, and what is it called. Some add-on files contain silly names like “latest -234.xpi” which is not very useful when trying to find it later
Open the add-on window in Thunderbird, there is a button on the left side of the search window.
Click this and from the subsequent menu select Install Add-on From File.
You will need to navigate in the file picker to where you saved the XPI file and select it to complete the install.
- Open the add-ons manager ( then )
- Drag your downloaded XPI file to the add-on manager tab and drop it.
If you are using Windows, you can even skip the desktop bit. Open your browser and Thunderbird side by side, with Thunderbird’s Add-ons tab displayed. Drag the link directly from the browser onto Thunderbird’s Add-on tab. The main advantage of this method is that you don’t need to actually save a copy of the add-on on your hard disk before it is installed.