Show HN: TabMail, an Open-Source AI Email Client for Thunderbird and iPhone

Summary

TabMail is an AI-focused email client developed by a solo developer as a Thunderbird add-on and an iPhone app. Both clients have been released as open source under the MPL 2.0 license. Users can review a prepared email reply, ask the system to change it, and ask questions about information in their inbox or calendar. The Thunderbird version is designed to support keyboard-driven use, while the iPhone app is intended to support spoken interaction. TabMail’s AI backend remains closed because the developer must obtain computing capacity from large-language-model providers. The developer says email and calendar processing uses zero data retention: content may be sent to providers for AI processing, but it is not retained on TabMail’s servers. Search remains on the device. The Thunderbird add-on is currently distributed from TabMail’s website because it uses the Experiments API for capabilities that are not supported by Manifest V3. The project is being shared for community feedback, and source code is available for both the Thunderbird and iOS clients.