78 Add-ons in this Collection
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.
FoxyProxy Standard by Eric H. Jung, groeg, others
FoxyProxy is an advanced proxy management tool that completely replaces Firefox's limited proxying capabilities. For a simpler tool and less advanced configuration options, please use FoxyProxy Basic.
Allows bidirectional access to Google Calendar
Adds some tools to import and export folders and messages
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).
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.
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.
Contact Tabs enhances Thunderbird to give you quick access to all your contacts directly from Thunderbird's main window: Use the powerful search field to find your contacts and open them in a new tab for viewing and editing.
This addon provides a conversation view for Thunderbird, grouping messages together and allowing you to reply "inline" thus providing a more efficient workflow.
The latest version is compatible with Thunderbird 38+ only (see below for details).