Add-ons
Most Popular Extensions
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Lightning
Requires Restart
Featured
Organize your schedule and life's important events in a calendar that's fully integrated with your Thunderbird email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
ImportExportTools
Requires Restart
Adds some tools to import and export folders and messages
Provider for Google Calendar
Requires Restart
Allows bidirectional access to Google Calendar
Enigmail
Featured
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
LookOut (fix version)
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).
Support: Thunderbird and SeaMonkey
gContactSync
Requires Restart
Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.
Send Later
Requires Restart
True "Send Later" functionality to schedule the time for sending an email.
Mail Redirect
Addressbooks Synchronizer
Requires Restart
Synchronizes selected addressbooks with other instances of thunderbird
using ftp/webdav/imap servers
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).
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.
Display Mail User Agent
Requires Restart
Displays icon for user agent of received mails.
Confirm-Address
QuickFolders (Tabbed Folders)
Requires Restart
The "Swiss army knife" of folders. Turn your favorites into tabs - open folders and subfolders, move mails without scrolling around or searching. powerful + easy.
See new mail at a glance after automatic filtering - supports quickFilters addon!
SmartTemplate4
Requires Restart
SmartTemplate4 offers an easy way to automatically create customized replies by auto-inserting various mail headers. Templates can be created for every account as well as for the default (all email accounts). Also supports the Stationery Add-on.
MinimizeToTray revived
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.
Theme Font & Size Changer for ThunderBird
Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.
To create your own collections, you must have a Mozilla Add-ons account.
