Most Popular Extensions
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 ...
Simple Locale Switcher Requires Restart
An easier management of the user interface language
CardBook Requires Restart Featured
This addon provides a conversation view for Thunderbird, grouping messages together and allowing you to reply "inline" thus providing a more efficient workflow.
Display Mail User Agent Requires Restart
Displays icon for user agent of received mails.
Color Folders Requires Restart
Color your Folder Treeview Icons!
rikaichan Requires Restart
Japanese to English/German/French/Russian dictionary. Just hover the mouse on top of a word, and a popup appears. Automatically de-inflects verbs and adjectives. Detailed kanji view...
Confirm-Address Requires Restart
Confirm E-mail address before sending mail
Reinstates the extensions.checkCompatibility preference without respect to the current application version.
Lightning Calendar Tabs Requires Restart
Displays tabs which allows quick navigation between time periods in Lightning calendar. All views of calendar are supported. Color of tab texts can be adjusted.
Rikaichan Japanese-English Dictionary File Requires Restart
This is a dictionary file add-on for the Rikaichan extension.
ThunderPEC Requires Restart
ThunderPEC semplifica la gestione della Posta Elettronica Certificata (PEC) e delle comunicazioni PCT e FatturaPA in Thunderbird.
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7s small view, Fx 4-12s large view & Tb 5-14) for current Firefox, Thunderbird and Seamonkey versions.
Beta builds on versions page!
Folderpane Tools Requires Restart
Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.
Copy Plain Text 2 Requires Restart
Copies text without formatting
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!
ProfileSwitcher Requires Restart
It adds some options to launch easily other profiles and the Profile Manager.
XNote++ Requires Restart
Persistent sticky notes for Thunderbird associated to mails.
This is a port to Thunderbird >= 3 based on XNote 2.1.0 ( https://addons.mozilla.org/en-US/thunderbird/addon/3093 ) with bugfixes and additional features.
Asks for the master password at startup (fixes multiple password prompt)
Font Finder Requires Restart
FontFinder is created for designers, developers and typographers. It allows a user to analyze the font information of any element on a page, copy any piece(s) of that information to the clipboard, and perform inline replacements to test new layouts.