Instellings Add-ons, extensions, and themes Enhance product functionality with add-ons, extensions, and themes. Almal All articles and threads Add-ons, extensions, and themes In Engels Filelink for Large Attachments Permission request messages for Thunderbird extensions Open Search Thunderbird add-ons - frequently asked questions Installing an Add-on in Thunderbird How to Install and Use another Language in the Dictionary on Thunderbird Install themes to change the look of Thunderbird Unified Toolbar How to Customize the New Mail Sound How to Customize Toolbars Certificates Add-Ons FAQ Add Search Engine to Open Search 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 Unable to uninstall add-ons (extensions or themes) userChrome.css and .js and userContent are unsupported