Most Popular Extensions
Add-on has now been discontinued, see below.
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.
ThunderPEC Requires Restart
ThunderPEC semplifica la gestione della Posta Elettronica Certificata (PEC) e delle comunicazioni PCT e FatturaPA in Thunderbird.
This addon provides a conversation view for Thunderbird, grouping messages together and allowing you to reply "inline" thus providing a more efficient workflow.
Confirm-Address Requires Restart
Confirm E-mail address before sending mail
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.
Display Mail User Agent Requires Restart
Displays icon for user agent of received mails.
ExQuilla for Exchange Requires Restart
Thunderbird email accounts connecting to Microsoft Exchange Web Services.
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!
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.
TbSync is a central user interface to manage cloud accounts and synchronize their contact, task and calendar information with Thunderbird.
SmartTemplate4 Requires Restart
SmartTemplate4 offers an easy way to automatically create customized replies by auto-inserting various mail headers. Templates can be created for every account as well as for the default (all email accounts). Also supports the Stationery Add-on.
Check and Send Requires Restart
Check the message contents and addresses before you send the message...
Fixed version (no 90 day timer till silent failure) of the popular "Theme Font & Size Changer for Thunderbird" addon
Flex Confirm Mail Requires Restart
Confirm mail address and attachments based on flexible rules.
Auto Resize Image Requires Restart
Resizer for inline and attachment images (JPEG, PNG, BMP and GIF image formats).
All platforms are supported (Windows, Linux and Macintosh).
LightningButton Requires Restart
Toolbar-Buttons for Lightning; advances the feature to get rid of the tabbar.
Asks for the master password at startup (fixes multiple password prompt)
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.
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.