How to Change the Default Browser in Thunderbird

This article explains how to change the default browser Thunderbird uses to open URLs. These instructions apply to Thunderbird 91.10, so update to the latest version before you begin.

Set the Default Browser in Thunderbird

Thunderbird usually passes the event off to your default web browser. Under normal circumstances, this all goes off without a hitch. However, if things go wrong, you need to know how to tell Thunderbird precisely which web browser you want it to use.

1. Select Menu (the three lines) > Preferences.

2. Scroll down to the bottom of the Preferences window and select Config Editor.

3. Select Show All to reveal the Config Editor settings.

4. Use the search at the top of the Config Editor window to look for network.protocol-handler.warn-external.http.

   Then, double-click network.protocol-handler.warn-external.http and network.protocol-handler.warn-external.https to set their values to True.

5. Close the Config Editor, then open a link in an email. In the pop-up window, select Choose next to Choose other Application.

6. Find and select the application file for the browser you wish to make the default. For example, to choose Chrome in Windows, go to C: > Program Files > Google > Chrome > Application.

7. Check the box next to Always use this application to open https/http links, then select Open Link.

8. Restart Thunderbird. If everything worked, Thunderbird will send clicks on URLs to whatever browser you selected.

Pro Tip

By following the steps above, you can set Thunderbird to use a web browser other than the default one the rest of your computer's applications use. It could be handy if you're concerned about viruses coming in through emails and only want to view these web pages in a high-security web browser.

And, you can handle HTTP-based URLs with one browser and HTTPS-based ones with another. Again, this could be something to consider for security and privacy issues. While you may trust your HTTPS (encrypted) requests to any of your installed web browsers, you may want your HTTP (non-encrypted) requests handled by a different browser.

To change which web browser to use in the future, go to Thunderbird Preferences and scroll down to the Files & Attachments section. Next to http and https, select the dropdown under Action to pick a new browser.