Send Later

True "Send Later" functionality to schedule the time for sending an email.

iCanban - Kanban with ICAL

Date Time Formatter

Shows relative date-time in the column.
Note: you need to click "Select columns to display" and then -> "Relative Date/Time"

All Seeing Time

Shows time city/state and 24-hour local time for NANPA & international codes. Area Code locator

Show in Mail URL for macOS Calendar

Provides the 'Show in Mail' URL to be added in an iOS/macOS Calendar event referering to the message ID. Can also be customized for gmail URLs using the custom URL format in the extension preferences.

Lightning Invitation Notifier | LIN

This extension is an extension to Mozilla Lightning for Thunderbird.
It shows a toast message and opens the invitations window when an invitation arrives.

TodayReplacer

Ersetzt [[TODAY]] beim Senden durch das Datum im gewünschten Format.

CalendarSearchExport

Exports the results of a search in calendars

Provider for Exchange ActiveSync

Add sync support for Exchange ActiveSync (EAS v2.5 & v14.0) accounts to TbSync

TbSync

TbSync is a central user interface to manage cloud accounts and synchronize their contact, task and calendar information with Thunderbird.

Lightning Calendar Tabs

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.

Mahoor-Iranian-Date

This add-on adds a new column called "Persian Date" in recent versions in message list containing Iranian Date.

It is reimplementation of Iranian date for Thunderbird 78+ and 115+. The source is based on Full address column by Łukasz Kosson.

Birthday Calendar

Adds calendars containing the birthdays from your address books.

EDS Calendar Integration

Integrates calendars events with Gnome clock applet

Calendar/Project Tools: Gantt-/Year View, Planner

*Display Gantt View and Year View
*Task Time Planning: daily, distribute your open tasks into open time slots.
*Show parent/child relationships for tasks

More Snooze

This add allow to customize the snooze delay when snooze popup appears (lightning required).

Allday Tasks

Thunderbird lacks the ability to create and manage allday tasks. This add-on adds these capabilities.

Macro Template

Macro Template is to replace mail templates with macros for date formatting.

Create Calendar events from mail content

This plugin offers to create new events based on the email subject and content

Outlook Calendar - Quick Access

This extension adds a simple button to your Spaces toolbar that opens in a new tab, providing you with one-click access to Outlook Calendar.