Settings
Add-ons, extensions, and themes
Enhance product functionality with add-ons, extensions, and themes.
Filelink for Large Attachments
Messages with large attachments are often rejected by mail servers. Thunderbird can use web-based storage services to send large file attachments.
Permission request messages for Thunderbird extensions
More information about each permission request you may encounter when installing an extension into Thunderbird.
Installing an Add-on in Thunderbird
Add-ons add functionality to Thunderbird or change its appearance. Learn how to install add-ons to Thunderbird.
How to Customize the New Mail Sound
Learn how to customize the sound that plays when a new email message is received.
Thunderbird add-ons - frequently asked questions
Add-ons are extensions and other additions that add new functionality to Thunderbird or change its appearance.
How to Customize Toolbars
This article explains how to customize the position and contents of Thunderbird toolbars.
Install themes to change the look of Thunderbird
A theme is a type of add-on which changes the visual appearance of Thunderbird. Learn how to find, install, and manage themes within Thunderbird.
Unified Toolbar
Intro to the Unified Toolbar and how to customize the buttons for the different toolbars for: Mail, Address Book, Calendar, Tasks, Chat and Settings "Spaces."
Certificates
How to Install and Use another Language in the Dictionary on Thunderbird
How to install and use additional language dictionaries on Thunderbird.
Add-Ons FAQ
Open Search
Instantly take part of a message and search for it in Bing, Yahoo, Twitter or other websites.
Add Search Engine to Open Search
Open Search enables Thunderbird users to search various websites from within Thunderbird. This article describes how to add additional websites to the Open Search interface.
How can I digitally sign and encrypt emails?
Installing and Using another Language in the Dictionary
Unable to install add-ons (extensions or themes) in Thunderbird
This article describes various reasons that would cause an add-on not to be able to be installed and what you can do to fix the issue.
Unable to uninstall add-ons (extensions or themes)
This article describes how to uninstall an extension or theme that can't be removed normally.
userChrome.css and .js and userContent are unsupported
userChrome.css, userChrome.js, userContent.css and userContent.js are unsupported because they can break at any time and are difficult to troubleshoot.