Extensions by Weekly Downloads
Enigmail Requires Restart Featured
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
Personas (now known as lightweight themes) are free, easy-to-install "skins" for Firefox. Personas Plus extends that built-in functionality to give you even more control and easier access to new, popular, and your own favorite themes.
KeeFox Requires Restart
Simple and secure password management. Login automatically, never forget another password, stay in control of your passwords and improve their security. Powered by the world-renowned KeePass Password Safe.
gContactSync Requires Restart
Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.
Clippings Requires Restart
Save frequently-entered text for pasting later.
CardBook Requires Restart Featured
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
'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!
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.
MinimizeToTray revived Requires Restart
Minimizes windows into the system tray.
ReminderFox Requires Restart
ReminderFox displays and manages lists of reminders and ToDo's. ReminderFox makes sure you remember all of your important dates via easy-to-use lists, alerts, and alarms, right in your browser without the need for a separate calendar program.
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.
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.
Mail Merge Requires Restart Featured
Mass Mail and Personal Mail
Website Blocker Requires Restart
Block websites you don't want the browser to get into.
Block by a whole domain name or a specific address.
Block until further notice or until a certain date.
Simple Locale Switcher Requires Restart
An easier management of the user interface language
Saved Password Editor Requires Restart
Adds the ability to create and edit entries in the password manager.