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.

TodayReplacer

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

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.

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

Message Links 4 events

Allows to use links to messages in the description field of events and task

Allday Tasks

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

iCanban - Kanban with ICAL

ElsHelp

Extension for ElSchool diary

All Events

Define your own time ranges for appointment searches

Date Time Formatter

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

CalendarSearchExport

Exports the results of a search in calendars

Multimonth view

Multimonth View allows users to display multiple months in a single calendar view,

Open Google Tabs

Open up Google Calendar, Notes, and Microsoft Outlook in a new tab.

Dropbox Paper

How Does It Work?
Once you install the add-on, a new icon will appear in the Thunderbird toolbar. Simply click on the icon, and it will open the Dropbox Paper tab.

Will the Dropbox Paper Add-on Collect My Data?
Never.

Copy Timestamp

Copy the timestamp and/or email addresses of the sender, recipient, etc. to the clipboard in various formats.

Proton Calendar Toolbar Button

Adds a Proton Calendar button to the toolbar. The button simply opens a new tab with the https://calendar.proton.me webpage.

Outlook/Teams Appointments

Get the hidden appointment from an email from outlook/teams as a .ics-file - Icon: https://fontawesome.com/

Birthday Calendar

Adds calendars containing the birthdays from your address books.