Calendar and Date/Time
Send Later Requires Restart Featured
True "Send Later" functionality to schedule the time for sending an email.
Provider for Exchange ActiveSync Requires Restart
Add sync support for Exchange ActiveSync (EAS v2.5 & v14.0) accounts to TbSync
TbSync Requires Restart Featured
TbSync is a central user interface to manage cloud accounts and synchronize their contact, task and calendar information with Thunderbird.
Provider for CalDAV & CardDAV Requires Restart
This extension adds support for CalDAV & CardDAV accounts to the Thunderbird Sync manager "TbSync".
Enhanced Date Formatter Requires Restart
Configure the 'Date' and 'Received' columns and displayed date in the message pane using custom formats. You can even use different date formats for emails with today's date, yesterday's date, dates in the last week, or dates older than a week.
Show Calendar Week Requires Restart
Shows the calendar week Thunderbird/Lightning calendar's moth and multi-week view.
LCD Clock Requires Restart
displays a LCD Clock in your Toolbar
Gantt View Requires Restart
Gantt Chart view for Sunbird/Lightning
Todo.txt Requires Restart
Thunderbird extension for the Todo.txt application
EDS Calendar Integration Requires Restart
Integrates calendars events with Gnome clock applet
AdvancedTasks Requires Restart
Thunderbirds Lightning Extension: Allows the use of Markdown in Task descriptions and renders them as HTML in the TaskView.
MultiBirthdaysReminder Requires Restart
This addon is now integrated into the new address book CardBook and thus it is no longer maintained
Adds the Google Calendar web interface in a new Thunderbird tab. Creating and viewing events works like in a browser (Firefox, Chrome, ...)
Reply Monitor Requires Restart
**This is NOT COMPATIBLE with Thunderbird 31 or newer versions**
Keep track of your emails and replies (Lightning is required).
Note: the name of this add-on has been changed to Reply Monitor because the previous name is a registered trademark.
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.
More Snooze Requires Restart
This add allow to customize the snooze delay when snooze popup appears (lightning required).
SanRockstar Requires Restart
Purge Events Plus Requires Restart
Purge events from Sunbird and Lightning files and thereby cleanes the calendar
Add Google Tabs to Thunderbird! Services supported by G-Hub Lite: Calendar, Contacts, Drive, Docs, Sheets, Slides, Maps, Search, & Voice. Need G Suite / Google Apps support? Check out G-Hub Pro: https://www.schiffner.com/index.php/software/g-hub-pro
StormCows Requires Restart
Allows two-way access between Remember The Milk and calendar events or todo items.