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.

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.

Thunderbird add-ons - frequently asked questions

Add-ons are extensions and other additions that add new functionality to Thunderbird or change its appearance.

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

How can I digitally sign and encrypt emails?

Installing and Using another Language in the Dictionary

How to Customize Toolbars

This article explains how to customize the position and contents of Thunderbird toolbars.

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.