On Linux, Thunderbird stubbornly ignores my desktop environments’ default browser and insisted on opening web pages in Firefox. Here’s how I fix it.
Thunderbird’s documentation claims that it respects default browser settings. Yeah, right. On my every installation Thunderbird would open all URLs in Firefox regardless of desktop environments’ settings. This behavior is consistent regardless of Thunderbird version, Linux distribution, or desktop environment.
After spending many fruitless hours chasing blind alleys in Thunderbird’s documentation, I finally found that resetting the relevant mime types did the trick. This can be done either in Thunderbird’s GUI (easier, safer) or manually in a text editor. Here’s how:
The GUI way
Open Thunderbird’s config editor (Menu Button – Preferences – Preferences – Advanced – General – Config Editor). In the filter, search for the entries:
Set the value of each entries to true, which you can do this by double-clicking each entry. Close the config editor window and the Thunderbird Preferences window.
Click on an http link in Thunderbird; you will be presented with the “Launch Application” window. Press the “Choose” button on this window and select your desktop environment’s default browser helper application. What this is depends upon your platform: commonly used ones are xdg-open, www-browser, and sensible-browser. Also check the box to remember this choice and make this selection permanent. Repeat this step for the https and ftp protocols.
Once completed, Thunderbird will respect your desktop environment’s default browser.
A closing rant: This issue should not exist. Other Linux applications have no problem respecting desktop environments’ preferences. And just to play devil’s advocate for a moment, if it must exist then the fix should be documented. As it was, Thunderbird’s help center was useless, and I was trapped for many needless hours in a maze of twisty little Mozillazine passages, all alike.