These instructions apply to Thunderbird 91.10, so update to the latest version before you begin.
Under normal circumstances, this all goes off without a hitch.
SelectMenu(the three lines) >Preferences.
Then, double-clicknetwork.protocol-handler.warn-external.httpandnetwork.protocol-handler.warn-external.httpsto set their values toTrue.
Find and snag the tool file for the web app you wish to make the default.
Check the box next toAlways use this software to open https/http links, then selectOpen Link.
If everything worked, Thunderbird will send clicks on URLs to whatever internet tool you selected.
This technique does not change your default web online window across all of your applications.
This setting affects Thunderbird only.
And, you could handle HTTP-based URLs with one web app and HTTPS-based ones with another.
Again, this could be something to consider for security and privacy issues.
Next tohttpandhttps, snag the dropdown underActionto pick a new surfing app.
On Linux, this change should work on your particular distribution with your specific desktop environment.
