K-9 Mail is a 100% open source, privacy focused email client for Android
K-9 Mail — description
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 at https://forum.k9mail.app
Want to help?
K-9 Mail is now part of the Thunderbird family and remains a community developed project. If you're interested in helping to improve the app, please join us! You can find our bug tracker, source code, and wiki at https://github.com/thunderbird/thunderbird-android We're always happy to welcome new developers, designers, documenters, translators, bug triagers and friends.
Latest version
Version
21.0
Update
Jul 20, 2026
Package ID
com.fsck.k9
What's new
Jul 20, 2026
K-9 Mail version 21.0
Changed: - Animation setting now allows On, Off, and System Default options - Modernized 'Fetching mail' account settings screen - Modernized 'Composition defaults' screen
Fixed: - Application could crash due to memory exhaustion - Application could crash when rendering long messages - Inline images were shown as attachments instead of displaying in message - Server search results could disappear - Manage Folders opened the wrong account instead of selected account