PlugOS adoption note: K-9 Mail used as the built-in mail client in a privacy-focused OS

Hi K-9 Mail / Thunderbird for Android team,

I’d like to share a real-world adoption note: K-9 Mail is preinstalled as the default email client in PlugOS.

PlugOS is a security- and privacy-focused Android-based system with a plug-and-play hardware form factor that works across iOS, Android, Windows and MacOS. It follows a clear design principle: the host phone is treated as an untrusted terminal, while the OS, apps, and sensitive user data run on a separate device.

All built-in applications in PlugOS are selected with a strong emphasis on security, privacy, and long-term maintainability, which is why we chose K-9 Mail as the default mail client.

Thanks for maintaining K-9 Mail and for your long-term commitment to open standards and user privacy. It’s great to see the project being used in security-oriented systems.

This issue is an adoption note about K-9 Mail being preinstalled in PlugOS; it names no files, tests, or entry points. There is no requested documentation change or completion condition to investigate.