K-9 Mail

K-9 Mail is an open-source email client for Android.

Download

K-9 Mail can be downloaded from a couple of sources:

• Google Play
• F-Droid
• Github Releases

You might also be interested in becoming a tester to get an early look at new versions.

Release Notes

Check out the Release Notes to find out what changed in each version of K-9 Mail. For a more up to date list of changes, see the XML Changelog.

Need Help?

If the app is not behaving like it should, you might find these resources helpful:

• Frequently Asked Questions
• Support Forum

Translations

Interested in helping to translate K-9 Mail? Contribute here:

• K-9 Mail localization

Contributing

We welcome contributions from everyone. Please see the CONTRIBUTING guide for more information.

Forking

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.

Architecture Decision Records (ADR)

We use Architecture Decision Records to document the architectural decisions made in the development of K-9 Mail. 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.

Communication

Aside from discussing changes in pull requests and issues we use the following communication services:

• Matrix: #tb-android:mozilla.org

Security

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.

License

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.