Most Popular Extensions

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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 (265)
30,473 users

Simple Locale Switcher Requires Restart

An easier management of the user interface language

Rated 5 out of 5 stars (14)
29,263 users

CardBook Requires Restart Featured

A new Thunderbird address book based on the CardDAV and vCard standards.

Twitter: @CardBookAddon
Forum: https://cardbook.6660.eu/

Rated 4 out of 5 stars (157)
28,453 users

Thunderbird Conversations

This addon provides a conversation view for Thunderbird, grouping messages together and allowing you to reply "inline" thus providing a more efficient workflow.

Rated 4 out of 5 stars (424)
28,019 users

Display Mail User Agent Requires Restart

Displays icon for user agent of received mails.

Rated 4 out of 5 stars (106)
26,891 users

Color Folders Requires Restart

Color your Folder Treeview Icons!

Rated 4 out of 5 stars (126)
26,016 users

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...

Rated 5 out of 5 stars (135)
25,717 users

Confirm-Address Requires Restart

Confirm E-mail address before sending mail

Rated 4 out of 5 stars (49)
25,623 users

Disable Add-on Compatibility Checks

Reinstates the extensions.checkCompatibility preference without respect to the current application version.

Rated 4 out of 5 stars (118)
25,385 users

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.

Rated 4 out of 5 stars (11)
25,005 users

Rikaichan Japanese-English Dictionary File Requires Restart

This is a dictionary file add-on for the Rikaichan extension.

Rated 5 out of 5 stars (10)
23,757 users

ThunderPEC Requires Restart

ThunderPEC semplifica la gestione della Posta Elettronica Certificata (PEC) e delle comunicazioni PCT e FatturaPA in Thunderbird.

Rated 5 out of 5 stars (11)
23,221 users

Classic Toolbar Buttons [Fx45-56][Tb24-58]

'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!

Rated 5 out of 5 stars (143)
22,718 users

Folderpane Tools Requires Restart

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

Rated 4 out of 5 stars (122)
21,545 users

Copy Plain Text 2 Requires Restart

Copies text without formatting

Rated 5 out of 5 stars (94)
21,309 users

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!

Rated 5 out of 5 stars (120)
21,186 users

ProfileSwitcher Requires Restart

It adds some options to launch easily other profiles and the Profile Manager.

Rated 4 out of 5 stars (110)
21,119 users

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.

Rated 5 out of 5 stars (67)
20,362 users

StartupMaster

Asks for the master password at startup (fixes multiple password prompt)

Rated 4 out of 5 stars (269)
19,642 users

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.

Rated 4 out of 5 stars (79)
18,752 users