Mozilla Thunderbird is perhaps one of the best email clients out there that do almost everything — from integration with Gmail or Outlook, customizable add-ons, setting up of private email servers and accounts, syncing across multiple platforms Windows, Linus, macOS and much more.

So if you’re one who’s an avid fan of Thunderbird and you’re looking to customize it to a dark theme interface, then you’ve come to the right place. 🙂

In this guide, we will show you how you step-by-step on how to enable dark theme in Mozilla Thunderbird in 3 minutes.

Without further ado, let’s jump right in.



How to Enable Dark Theme In Mozilla Thunderbird: 5 Steps


  1. Go ahead launch your Thunderbird application on your Mac or PC and then press the Alt button on your keyboard to have the top-menu appear (as shown below).

Mozilla Thunderbird email client


  1. Next, from the menu, select Tools and then click on Add-ons.

Enable Dark Theme In Mozilla Thunderbird


  1. Now, in the Add-ons Manager page, click on the Themes section from the left-hand sidebar (its the one with the brush icon).

Add Ons Manager in Mozilla


  1. Then next to the Dark (theme) click on the Enable button to activate the dark theme.

Enable Dark Theme In Mozilla Thunderbird


  1. Lastly, if the dark theme doesn’t appear automatically, simply restart your Thunderbird application to have the changes take effect.

Enable Dark Theme In Mozilla Thunderbird


Voila! Now if you ever change your mind and decide that light mode is more suited to your liking, then simply follow the above five steps and then click on the Disable button right next to Dark (theme) instead


Wait, hollup, how to make Mozilla Thunderbird use the dark theme for the entire interface? 🧐

Since the dark theme that comes with Thunderbird (which you enabled above) only applies to certain parts of the interface such as the menu bar, buttons, and toolbar, there is an alternative option to have dark mode take effect completely of the Thunderbird interface.

Thanks to a user named Steva, who built a third-party Thunderbird extension called TT DeepDark (free) which does exactly its name hints — turn your Thunderbird application completely dark (as shown below).


Enable Dark Theme In Mozilla Thunderbird


To download the extension, simply head over to the TT DeepDark Thunderbird extensions page. Once you’ve installed it, it will appear in your Add-ons Manager page as shown in Step 3 (above). From there simply hit the Enable button and restart your Thunderbird application to have the extension take effect.

If by any chance you do find the theme useful, kindly make a small contribution to Steva. This helps him keep the extension updated in the long run. 🙂

We hope that the information above has helped enable the dark mode on your Thunderbird email client.  

Feel free to go through the tips and advice from the many helpful comments posted by others below. 


If this guide was helpful, please share it. 🙂