Provider for Google Calendar Requires Restart
Allows bidirectional access to Google Calendar
Quicktext Requires Restart
Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.
ImportExportTools Requires Restart
Adds some tools to import and export folders and messages
Mail Redirect Requires Restart
Allow to redirect (a.k.a. "remail") mail messages to other recipients.
DOM Inspector Requires Restart
DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM can be navigated using a two-paned window displaying a variety of different views on the document and all nodes within.
Display Quota Requires Restart
This extension will display the current status of your IMAP quota in thunderbird's statusbar and will warn you when you reach a configurable limit...
Add-on has now been discontinued, see below.
LightningButton Requires Restart
Toolbar-Buttons for Lightning; advances the feature to get rid of the tabbar.
Calendar Tweaks Requires Restart
Allows several tweaks to the Thunderbird/Lightning calendar user interface including new selection styles and repeating event icons. Mimics the colors and styles found in MS Outlook.
Xpunge Requires Restart
Empties the Trash and Junk folders, and compacts folders in multiple Thunderbird accounts.
PrintingTools Requires Restart
Adds some options to print messages and addressbooks
FiltaQuilla Requires Restart
Adds many new mail filter actions - launch a file, suppress notification, remove star or tag, mark replied or unread, copy as "read", append text to subject.
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
MinimizeToTray revived Requires Restart
Minimizes windows into the system tray.
Add Signature Requires Restart
Simply add your signature manually (right mouse click) to your emails
IMAP Quota (Free Space) Requires Restart
This Thunderbird addon lets you customize the IMAP quota statusbar panel.
ThunderKeepPlus Requires Restart
Google Keep for Thunderbird
Display Mail User Agent T Requires Restart
Displays the mail program with which the selected mail was written
*This addon is compatible with Thunderbird after Web Extesnsions support. Since development and operation check are done on Daily, it may not work on normal Thunderbird.
Uploads your large attachments to your WebDAV account instead of sending them by email.
Rise of the Tools Requires Restart
Moves the toolbar back above the tabbar.