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Synchronise the calendars and contacts Fenritec Alpha in Thunderbird

13 September 2026 by
Nicolas Schwartz
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If you already use Thunderbird as your daily email client, you no longer need to open a browser tab to check your Fenritec Alpha calendar or search for a contact in your organisation's shared address book.

A dedicated extension allows you to integrate these two services directly into Thunderbird - calendar on one side, address book on the other - and keep them synchronised permanently with the Fenritec server.

Here’s how to install and configure it from A to Z.

Prerequisites


Before you begin, ensure you have:

- Thunderbird installed and functioning on your machine (version 153 or newer recommended).
- A Fenritec Alpha account active, with your login credentials at hand.
- The installation file for the extension (a `.xpi` file): Download

Note: The `.xpi` file is the standard format for Thunderbird extensions. No need to open or extract it: Thunderbird knows what to do with it.


Install the extension in Thunderbird


Launch Thunderbird, then open the add-ons manager. To do this, click on the menu button in the top right, then Add-ons and Themes.

In the left panel, select the tab Extensions. You can see the list of modules already installed.

At the top right of this list is a small gear ⚙️ : click on it. A dropdown menu opens — choose « Install a module from a file… ».

A navigation window appears. Go and find the `.xpi` file you just downloaded, select it and click on Open

Thunderbird then displays a confirmation window: click on Install

First connection to Fenritec Alpha


Once Thunderbird has restarted, look at the top toolbar. The extension has added a new icon - the Fenritec Alpha logo. Click on it.

A configuration window opens. Click on « New user », then enter your Fenritec Alpha work email address. Then click on « Connect »

An authentication page will appear: enter your usual Fenritec Alpha credentials and confirm. The connection is then established with the server, securely.

At this point, the extension is installed and authenticated, but Thunderbird is not yet synchronising anything: you need to specify which calendars and address books to retrieve.

Select the calendars and address books


Back in the extension window, click on the button « Discover ». The extension queries the Fenritec Alpha server and compiles a complete list of the resources you have access to: your personal calendars, the shared agendas of your colleagues, the individual and collective address books of your organisation.

Tick the calendars and address books you wish to see appear in Thunderbird. The initial synchronisation starts immediately: depending on the volume of data, it may take from a few seconds to a minute.

Check that everything is working


Switch to the Calendar tab in Thunderbird. Your Fenritec Alpha calendars are now listed in the left sidebar, with a unique colour code for each. 

Create an appointment in one of them: it will be replicated on the Fenritec server, and visible to other participants if the agenda is shared. Conversely, an appointment added from the Fenritec web interface will appear in Thunderbird at the next synchronisation.

The same logic applies to contacts: open the Addresses. Your Fenritec Alpha address books are present. You can search, create, or modify a record - changes are propagated in both directions.

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