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Thunderbird for Android is a powerful, privacy-focused email app. Effortlessly manage multiple email accounts from one app, with a Unified Inbox option for maximum productivity. Built on open-source technology and supported by a dedicated team of developers alongside a global community of volunteers, Thunderbird never treats your private data as a product.

Thunderbird for Android is based on K-9 Mail, which comes with a rich history of success and functionality in open source email.

Thunderbird for Android can be downloaded from a couple of sources:

• Thunderbird on Google Play or F-Droid
• Thunderbird Beta on Google Play or F-Droid
• Github Releases
• FFUpdater allows installing the latest versions from ftp.mozilla.org

By using Thunderbird for Android Beta, you have early access to current development and are able to try new features earlier.

Check out the Release Notes to find out what changed in each version of Thunderbird for Android.

If the app is not behaving like it should, or you are not sure if you’ve encountered a bug:

• Check out our knowledge base and frequently asked questions
• Ask a question on our support forum

If you are certain you’ve identified a bug in Thunderbird for Android and would like to help fix it:

• File an issue on our GitHub issue tracker

If you have an idea how to improve Thunderbird for Android:

• Tell us about and vote on your feature ideas on connect.mozilla.org.
• Join the discussion about the latest changes in the Thunderbird Android Beta Topicbox.

The Thunderbird Community uses Matrix to communicate:

• General chat about Thunderbird for Android and K-9 Mail: #tb-android:mozilla.org
• Development and other ways to contribute: #tb-android-dev:mozilla.org
• Reach the broader Thunderbird Community in the community space

We welcome contributions from everyone.

• Development: Have you done a little bit of Kotlin? The CONTRIBUTING guide will help you get started
• Translations: Do you speak a language aside from English? Translating is easy and just takes a few minutes for your first success.
• We have a number of other contribution opportunities available.
• Thunderbird is supported solely by financial contributions from users like you.Make a financial contribution today!
• Make sure to check out the Mozilla Community Participation Guidelines.

We use Architecture Decision Records to document the architectural decisions made in the development of Thunderbird for Android. You can find them in the docs/architecture/adr directory.

For more information about our ADRs, please see the ADRs README.

We encourage team members and contributors to read through our ADRs to understand the architectural decisions that have shaped this project so far. Feel free to propose new ADRs or suggest modifications to existing ones as needed.

The code in this repository was undergoing an extensive security audit in collaboration with the Open Source Technology Improvement Fund (OSTIF) and 7ASecurity in the first half of 2023. For more details, see our blog post.

You can report a security vulnerability through the respective issues form.

These are the SHA-256 fingerprints for our signing certificates:

• Thunderbird: B6:52:47:79:B3:DB:BC:5A:C1:7A:5A:C2:71:DD:B2:9D:CF:BF:72:35:78:C2:38:E0:3C:3C:21:78:11:35:6D:D1
• Thunderbird Beta: 05:6B:FA:FB:45:02:49:50:2F:D9:22:62:28:70:4C:25:29:E1:B8:22:DA:06:76:0D:47:A8:5C:95:57:74:1F:BD
• K-9 Mail: 55:C8:A5:23:B9:73:35:F5:BF:60:DF:E8:A9:F3:E1:DD:E7:44:51:6D:93:57:E8:0A:92:5B:7B:22:E4:F5:55:24

You can use the following command to retrieve and verify the certificate before installation:

In June 2022, K-9 Mail joined the Thunderbird family as the foundation for Thunderbird on Android. Since then, we’ve been updating both apps to give users the same solid experience, so it’s normal to notice that K-9 Mail and Thunderbird look and feel nearly identical. They’re built on the same code, and that’s intentional. You’ll notice some features are selectively enabled for Thunderbird as opposed to K-9 Mail, usually when they are simply a better fit for Thunderbird (like the import from K-9 functionality).

If you prefer the robot dog and would like to keep K-9 Mail around, you can find it here:

• K-9 Mail on Google Play
• K-9 Mail on F-Droid

If you want to use a fork of this project please ensure that you replace the OAuth client setup in the app-k9mail/src/{debug,release}/kotlin/app/k9mail/auth/K9OAuthConfigurationFactory.kt and app-thunderbird/src/{debug,daily,beta,release}/kotlin/net/thunderbird/android/auth/TbOAuthConfigurationFactory.kt with your own OAuth client setup and ensure that the redirectUri is different to the one used in the main project. This is to prevent conflicts with the main app when both are installed on the same device.