K-9 Mail

Android

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Freedom report

Two barsScore 6.9

Free tierA free tier is on its own pricing page
Runs widely1 of 6 device platforms
DocumentedPlans, terms and facts published

K-9 Mail is ranked #50 of 143 in email clients on Freedom251. It runs on Android. There is a free plan.

K-9 Mail plans and pricing

All plans

K-9 Mail Free Android email client · open source k9mail.app · 12 Oct 2026

Compared on email clients

Free plan: Yes
App coverage: mobile
Unified inbox: Yes
Offline access: Yes
Scheduled sending: No
Calendar tools: No

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The record

Purpose: K-9 Mail is an open source email client for Android with advanced features, designed to help users manage large volumes of email.
Accounts: The app supports multiple accounts and works with basically every email provider.
Inbox: Features include a unified inbox and per-account notifications.
Synchronization: The app supports automatic background synchronization or push notifications.
Search: The app supports local and server-side email search.
Encryption: K-9 Mail supports OpenPGP email encryption using PGP/MIME, and the listing says to install OpenKeychain to encrypt or decrypt email.
Other features: The maker lists white and dark themes, signatures, message flagging, multiple identities, keyboard shortcuts and attachment saving.
Privacy: The Google Play listing says the app shares no data with third parties and collects no data; it also says data is encrypted in transit.
Local data: The privacy notice says names, email messages and address books are stored and processed locally on the device and never sent to Mozilla.
OAuth: The privacy notice says OAuth authentication and synchronization happen directly between the app and the provider over an encrypted connection, without Mozilla-operated services.
Downloads: The maker lists Google Play, F-Droid and direct APK downloads from GitHub as download channels.
Support: The maker directs users with questions to its support forum and also lists Matrix and GitHub issue tracking for community interaction.
Documentation: The user manual page says the manual has been abandoned because the team lacks resources to keep it up to date; a historic version remains available.
License: K-9 Mail is licensed under Apache License, Version 2.0, and its source code is available on GitHub.
Price from: Free

Where it ranks on Freedom251

Best Email Clients in 2026#50 of 143

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Sources

k9mail.app· checked 12 Oct 2026
play.google.com/store/apps/details· checked 12 Oct 2026
k9mail.app/privacy· checked 12 Oct 2026
k9mail.app/download· checked 12 Oct 2026
k9mail.app/community· checked 12 Oct 2026
docs.k9mail.app· checked 12 Oct 2026
k9mail.app/about· checked 12 Oct 2026