Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
Organize your schedule and life's important events in a calendar that's fully integrated with your Thunderbird email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
Allows bidirectional access to Google Calendar
LookOut is a plugin which allows Thunderbird to interface with Microsoft's mail tools by decoding metadata and attachments encapsulated/embedded in a TNEF encoded attachment (aka winmail.dat).
Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.
Google and Zimbra contact sync for Thunderbird. (TB 24 and above NOT supported)
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.
Make your photos smaller, so they don't take forever to email or send to websites.
Toolbar-Buttons for Lightning; advances the feature to get rid of the tabbar.
Note from Mozilla: This add-on has been discontinued. Try MinimizeToTray Revived instead.
Minimize applications to the system tray.
It adds a button that can be put in toolbars and that open the addressbook in a new tab
add icons to buttons/menus/anywhere (CuteMenus - Crystal SVG not required)
Tasks and emails management in a Thunderbird extension. tasks are stored in emails folder and it's possible to link an email to a task.
See all in one, emails and tasks (no more pain to synchronize a task manager).
Collections are groups of related add-ons that anyone can create and share.Explore Collections