Most Popular Extensions
Remove Duplicate Messages (Alternate) Requires Restart
Search and remove messages which are the same as other messages in your mail folders (referred to as duplicates or dupes).
ImportExportTools Requires Restart
Adds some tools to import and export folders and messages
Mail Redirect Requires Restart
Allow to redirect (a.k.a. "remail") mail messages to other recipients.
DOM Inspector Requires Restart
DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM can be navigated using a two-paned window displaying a variety of different views on the document and all nodes within.
ChatZilla Requires Restart
A clean, easy to use and highly extensible Internet Relay Chat (IRC) client.
LookOut Requires Restart
LookOut is a plugin which allows Thunderbird to interface with Microsoft's mail tools by decoding metadata and attachments encapsulated/embedded in a TNEF encoded attachment (aka winmail.dat).
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
MinimizeToTray revived Requires Restart
Minimizes windows into the system tray.
FireTray Requires Restart
A system tray extension for Linux and Windows, allowing to set up custom icon, hiding to tray instead of closing, display the number of unread messages in mailing applications, and other features ...
MinimizeToTray Reanimated Requires Restart
MinimizeToTray Reanimated is an application mainly dedicated to Thunderbird to allow its minimization in the systray in one click. It is the update of MinimizeToTray Revived, which is not maintained anymore since the recent versions of Thunderbird.
Display Mail User Agent Requires Restart
Displays icon for user agent of received mails.
BiDi Mail UI Requires Restart
Direction control and BiDi-related charset misdetection correction
Join-NG Requires Restart
Join partial messages. Somewhat similar to MS Outlook Express "combine and decode".
Highlighter Requires Restart
Quickly highlight some text in Thunderbird message composing windows.
ThunderBirthDay Requires Restart
Display birthdays from the Thunderbird addressbooks as events in Lightning.
Adds toolbar buttons to the customize toolbar window in several programs including Firefox, Thunderbird and SeaMonkey. Some of the buttons make commonly preformed actions quicker, others add new functionality.
FlashGot Mass Downloader Requires Restart Featured
Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.
This extension enables true full screen mode in SeaMonkey for HTML5 video players, slide-shows, etc. and also for full screen invoked manually with the F11 key.
Folderpane Tools Requires Restart
Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.
Automatically do Archive/Copy/Delete/Move actions based on user defined rules