# K-9 Mail (open-source email app)

> K-9 Mail is a free, open-source email app for Android. Full-featured email client. It has 14,150 GitHub stars and is released under the Apache-2.0 license, and you can install it from F-Droid and Google Play.

K-9 Mail is an open source email client that works with basically every email provider. Features * Supports multiple accounts * Unified Inbox * Privacy-friendly (no tracking whatsoever, only connects to your email provider) * Automatic background synchronization or push notifications * Local and server-side search * OpenPGP email encryption (PGP/MIME) Install the app OpenKeychain: Easy PGP to encrypt/decrypt your emails using OpenPGP. Support If you're having trouble with K-9 Mail, ask for help in our support forum. Want to help? K-9 Mail is a community developed project. If you're interested in helping to improve the app, please join us!

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/thunderbird/thunderbird-android |
| Platforms | Android |
| Built with | Kotlin |
| GitHub stars | 14,150 |
| License | Apache-2.0 (open source) |
| F-Droid | https://f-droid.org/packages/com.fsck.k9/ (package com.fsck.k9) |
| F-Droid anti-features | none flagged |
| Google Play | https://play.google.com/store/apps/details?id=com.fsck.k9 |
| App Store | not linked |
| Website | https://k9mail.app/ |
| Official | yes (published by the organization behind the product) |
| Category | Email clients |
| Latest release | K9MAIL_24_0 (Oct 5, 2026) |
| Last commit | Oct 22, 2026 |

F-Droid builds its apps from source and flags anti-features: https://f-droid.org/en/docs/Anti-Features/

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