Most Popular Extensions
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.
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.
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).
MinimizeToTray revived Requires Restart
Minimizes windows into the system tray.
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
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.
Join-NG Requires Restart
Join partial messages. Somewhat similar to MS Outlook Express "combine and decode".
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.
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.
Automatically do Archive/Copy/Delete/Move actions based on user defined rules
Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
SeaTab-X-2 Requires Restart
Adds Firefox-style tab closers into SeaMonkey.
Reinstates the extensions.checkCompatibility preference without respect to the current application version.
The first and only download manager/accelerator built inside Firefox!
A fork of PDF.js with support for SeaMonkey 2.49.x.
ThunderBirthDay Requires Restart
Display birthdays from the Thunderbird addressbooks as events in Lightning.