Mozilla attacks: This is what the "Thundermail" ecosystem should look like

Florian Bodoky

9.4.2025

Translation: machine translated

Mozilla is building a new ecosystem. With an email service, smart calendar, file sharing system and local AI. It is to consist of privacy-friendly and open-source modules. The aim is to compete with data octopuses such as Gmail and the like.

"Thundermail" is the name of the new ambitious project from the Mozilla Foundation. The developers of the Thunderbird mail programme want to use it to get back into the conversation. This was once an open source client that lost users in droves due to convenient all-in-one platforms such as Gmail or Microsoft Office 365.

Now comes the big comeback: Thundermail is not just a new email service, but an entire suite of web services that will lay the foundation for an alternative, open source ecosystem - under the umbrella of "Thunderbird Pro".

Three modules without hidden AI

The centrepiece is the mail service of the same name, Thundermail. Users receive an email address under "thundermail.com" or "tb.pro" - and should be able to use a browser-based webmail interface in the medium term, similar to Gmail. Mozilla places particular emphasis on data protection: there will be no analysis of emails for advertising purposes, no transfer of data to third parties and no hidden use of AI training.

In addition to the email service, Mozilla is working on three modules that will be integrated into Thundermail:

Thunderbird Appointment

An appointment scheduling tool that allows you to schedule appointments, manage calendars and invite people to make appointments via links. Lean and simple, without excessive functionality.

Thunderbird Send

The rebirth of Firefox Send, which was discontinued in 2020. With the file sharing service, you should be able to send large files - similar to the WeTransfer service. According to Mozilla, sending is end-to-end encrypted and the service has been completely redeveloped so that the gaps and problems of the predecessor service can be ruled out.

Thunderbird Assist

An experimental AI module that relies on a local LLM (Large Language Model). The aim is intelligent email management that complies with data protection regulations. If the local system is too weak, Thunderbird Assist can optionally and with consent access a protected cloud solution based on Nvidia Confidential Compute. This is being developed in collaboration with the start-up Flower AI. However, Mozilla is still keeping quiet about its capabilities and functionality.

Open source, but not free

Mozilla remains true to its open source DNA. All Thunderbird Pro modules are to be developed open source and driven forward in close cooperation with the Community. Nevertheless, it is clear that the costs for development and operation are expensive. This can hardly be financed by donations alone. Mozilla is therefore aiming for multi-stage financing: Community members and active Thunderbird users will receive free access to the new services. Other users will pay an as yet unspecified fee. This will primarily be used to operate the server infrastructure.

In the long term, a slimmed-down plan is also planned. Free of charge, with limits on storage space or maximum file size when sending. It is not yet clear when the final version will be launched. You can join the waiting list here.

Florian Bodoky

Editor

Florian.Bodoky@digitecgalaxus.ch

I've been tinkering with digital networks ever since I found out how to activate both telephone channels on the ISDN card for greater bandwidth. As for the analogue variety, I've been doing that since I learned to talk. Though Winterthur is my adoptive home city, my heart still bleeds red and blue. more

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