thunderbird/thunderbird-android ? reverse-engineered prompt

Build me a privacy focused Android email app like Thunderbird for Android.

I want users to be able to add multiple email accounts, read and send mail, and switch between accounts or a unified inbox easily. The app should feel clean and modern, work well on phones, and respect privacy by not treating personal data like a product. Please make it solid, open source friendly, and ready to run on Android with the usual email app basics like inbox, sent mail, drafts, folders, search, and account setup.

If you need to check current docs or small platform details, look them up online so the implementation matches today’s Android best practices. Keep the app usable for both regular Thunderbird users and people coming from K 9 Mail, and make sure the core experience is reliable and polished.