Display Mail User Agent Requires Restart
Displays icon for user agent of received mails.
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!
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.
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 ...
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
Dorando keyconfig Requires Restart
A modified Dorando's addon to rebind keyboard shortcuts. It is designed to be a drop-in replacement, keeping your old settings. (See details for upgrade instructions.)
Simple Locale Switcher Requires Restart
An easier management of the user interface language
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7 small view, Fx4-12 large view & Tb5-14) for current Firefox, Thunderbird and Seamonkey versions.
FolderFlags Requires Restart
Allows users to edit the flags Thunderbird sets on folders.
IMAP Received Date Requires Restart
Make the “Received” column in IMAP folders show when messages were actually received.
This extension enables true full screen mode in SeaMonkey for HTML5 video players, slide-shows, etc. and also for full screen invoked manually with the F11 key.
Adds icons to buttons and/or menus.
Strike the 'T' key to sort messages by thread, strike the 'U' key to sort them unthreaded again, just like the 'G' key switches to Grouped By Sort view
SeaTab-X-2 Requires Restart
Adds Firefox-style tab closers into SeaMonkey.
Enhanced Priority Display Requires Restart
Enhanced thread pane display of message priorities.
Speed Dial & Start Page with flexible layout for fast access to sites via visual bookmarks
Text2Link Requires Restart
Text2Link is a simple and easy-to-use way to copy the text of a link, or to open URLs and send emails to addresses not marked-up as HTML links.
GNOMErunner Options Requires Restart
Allows to customize GNOMErunner theme
Add-on for Thunderbird that replaces the built-in notifications with OS native ones. It supports most Linux Desktop Environments as well as Windows 8.1/10.
CheckBoxMate Lefedor Edition Requires Restart
Check multiple checkboxes by drawing a rectangle around them. FF6 version.
I've made this version since i did need it for use with RTM,