Most Popular Extensions

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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).

Rated 4 out of 5 stars (217)
78,653 users

ImportExportTools Requires Restart

Adds some tools to import and export folders and messages

Rated 4 out of 5 stars (233)
50,530 users

Mail Redirect Requires Restart

Allow to redirect (a.k.a. "remail") mail messages to other recipients.

Rated 4 out of 5 stars (133)
34,765 users

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.

Rated 5 out of 5 stars (78)
28,694 users

ChatZilla Requires Restart

A clean, easy to use and highly extensible Internet Relay Chat (IRC) client.

Rated 4 out of 5 stars (150)
27,465 users

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).

Rated 4 out of 5 stars (157)
11,795 users

JavaScript Debugger Requires Restart

As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.

Venkman is the code name for Mozilla's JavaScript Debugger. Venkman aimed to provide a powerful JavaScript debugging environment for Mozilla based browsers.

Rated 4 out of 5 stars (52)
9,498 users

MinimizeToTray revived Requires Restart

Minimizes windows into the system tray.

Rated 4 out of 5 stars (395)
7,435 users

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 ...

Rated 4 out of 5 stars (287)
5,432 users

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.

Rated 4 out of 5 stars (135)
3,857 users

Display Mail User Agent Requires Restart

Displays icon for user agent of received mails.

Rated 4 out of 5 stars (112)
3,592 users

BiDi Mail UI Requires Restart

Direction control and BiDi-related charset misdetection correction

Rated 4 out of 5 stars (32)
2,380 users

Join-NG Requires Restart

Join partial messages. Somewhat similar to MS Outlook Express "combine and decode".

Rated 5 out of 5 stars (5)
2,313 users

Highlighter Requires Restart

Quickly highlight some text in Thunderbird message composing windows.

Rated 4 out of 5 stars (92)
1,977 users

ThunderBirthDay Requires Restart

Display birthdays from the Thunderbird addressbooks as events in Lightning.

Rated 4 out of 5 stars (94)
1,833 users

Toolbar Buttons

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.

Rated 4 out of 5 stars (371)
1,830 users

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.

Rated 5 out of 5 stars (890)
1,818 users

True Full Screen in SeaMonkey

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.

Rated 5 out of 5 stars (17)
1,671 users

Folderpane Tools Requires Restart

Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.

Rated 3 out of 5 stars (124)
1,662 users

Awesome Auto Archive

Automatically do Archive/Copy/Delete/Move actions based on user defined rules

Rated 4 out of 5 stars (46)
1,609 users