Most Popular Extensions
Lightning Requires Restart
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.
FlashGot Mass Downloader Requires Restart
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.
ImportExportTools Requires Restart
Adds some tools to import and export folders and messages
Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
Provider for Google Calendar Requires Restart
Allows bidirectional access to Google Calendar
This add-on allows you to export your saved passwords and disabled login hosts using XML or CSV files that can be imported later.
Note: This add-on won't work in Firefox 57. It may eventually if the APIs to access passwords are implemented.
If you are the kind of person who likes to have total control over every aspect of your downloads, "Download Status Bar" is the add-on you are looking for.
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).
Quick Locale Switcher Requires Restart
Allows you to quickly switch to a different language (User Interface, Spell Checker Dictionary and Website content) in your Mozilla application.
Manually sort folders Requires Restart
This extension allows you to manually sort (order) your folders in the folder pane of Thunderbird or automatically sort them, but in a better way. This extension also allows you to re-order accounts in the folder pane.
Enigmail Requires Restart Featured
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
SQLite Manager Requires Restart
Manage any SQLite database on your computer.
MinimizeToTray revived Requires Restart
Minimizes windows into the system tray.
Menu Wizard Requires Restart
Customize menus : Helps removing, moving and renaming menus and menu items
Colorize important menu for ease of use! (use Style (CSS))
Change or disable any of used keyboard shortcuts
Support: Firefox, Thunderbird and SeaMonkey
Add-ons Manager Context Menu Requires Restart
Add more items to Add-ons Manager context menu.
CompactHeader Requires Restart Featured
Add symbol in header plane to switch between compact and expanded view. Options to switch between one or two lines compact view, which buttons should be displayed in header pane. For Thunderbird 36 and older use version 2.0.9 (see version history)
Image Zoom Requires Restart
Adds zoom and rotation functionality for images...
gContactSync Requires Restart
Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.
Quicktext Requires Restart
Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.
UnMHT allows you to view MHT (MHTML) web archive format files, and save complete web pages, including text and graphics, into a single MHT file in Firefox/SeaMonkey.