K-9 Mail

K-9 Mail is a 100% open source, privacy focused email client for Android

K-9 Dog Walkers · com.fsck.k9

4.1 out of 5 (45 ratings) 5M+ downloads v24.0 10.9 MB Android 6.0+ PEGI 3 · Everyone

Download APK 10.9 MB All versions

Signature matches the Google Play version Details

At a glance

Latest version: v24.0 (39046)
Updated: Oct 7, 2026 (2 days ago)
APK size: 10.9 MB
Requires: Android 6.0+ (API 23)
CPU support: x86 32-bit, x86 64-bit, ARM 32-bit, ARM 64-bit
Category: Communication (app)
Listed since: Jan 13, 2021 (at least)
Permissions: 16 (2 sensitive)
Website: k9mail.github.io
Developer contact: [email protected]
Privacy: Developer's privacy policy

About this APK

K-9 Mail is an app by K-9 Dog Walkers in the Communication category, listed since at least January 2021. It includes native code for x86 32-bit, x86 64-bit, ARM 32-bit and ARM 64-bit, so it runs on practically every phone.

Since version 14.0, the APK shrank from 12.9 MB to 10.9 MB and the minimum Android version rose from 5.0 to 6.0. It asks for 16 permissions, 2 of them sensitive: camera and read contacts. It asks for the same permissions as version 23.1. The app offers in-app purchases through Google Play.

Ratings

4.1out of 545 ratings

5 ★51%
4 ★27%
3 ★13%
2 ★2%
1 ★7%

Ratings from users of the source store — not collected or verified by AAPKs.

What's new in v24.0

K-9 Mail version 23.1 Fixed: - Attachment filenames with non-ASCII characters were incorrectly decoded and saved

Description

From the listing uploaded by “appupdater”.

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.

Version history

7 versions are listed, going back to v14.0. Since v22.0 it requires Android 6.0+.

v24.0 LATEST Oct 7, 2026 10.9 MB TRUSTED v23.1 Sep 22, 2026 10.8 MB TRUSTED v23.0 Sep 10, 2026 10.8 MB TRUSTED v22.0 Oct 2, 2026 10.7 MB TRUSTED v16.1 Apr 20, 2026 13.4 MB TRUSTED

All 7 versions

Security & authenticity

Security rating: Trusted

Signing certificate

Signature matches the Google Play version Checked by the source store on Oct 7, 2026.
Certificate issued to “fsck.com” This is the certificate of the Google Play version.
Same certificate as the 3 other versions checked

Store checks and file details

Developer signature not checked yet Oct 7, 2026
Validated against Google Play Oct 7, 2026
Signed byCN=Jesse Vincent, OU=Open Source Labs, O=fsck.com, L=Somerville, ST=MA, C=US
Signing certificate (SHA-1)0F:1F:32:52:CB:A1:C9:4D:DD:61:86:DA:D5:A0:35:E9:6C:6E:E5:E3
File MD5fd545de4769a447e7b2ebb4ab338af7e
Uploaded by “appupdater” Gold tier · 117,810 followers · uploading since 2020

Scans and ratings come from the source store; the certificate comparisons are AAPKs's own, made from the files' published signatures (3 other versions compared). AAPKs doesn't scan files itself — compare the MD5 and signer after downloading.

Permissions (16)

K-9 Mail requests 16 permissions, 2 of them sensitive.

Camera Sensitive android.permission.CAMERA
Read contacts Sensitive android.permission.READ_CONTACTS
Control vibration android.permission.VIBRATE
Foreground service special use android.permission.FOREGROUND_SERVICE_SPECIAL_USE
Full network access android.permission.INTERNET
In-app purchases (Google Play Billing) com.android.vending.BILLING
Internal broadcast protection (app-defined) com.fsck.k9.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION
Prevent the device from sleeping android.permission.WAKE_LOCK
Read sync settings android.permission.READ_SYNC_SETTINGS
Run at startup android.permission.RECEIVE_BOOT_COMPLETED
Run foreground services android.permission.FOREGROUND_SERVICE
Schedule exact alarms android.permission.SCHEDULE_EXACT_ALARM
Show notifications android.permission.POST_NOTIFICATIONS
Use biometric hardware android.permission.USE_BIOMETRIC
Use fingerprint hardware android.permission.USE_FINGERPRINT
View network connections android.permission.ACCESS_NETWORK_STATE

K-9 Mail APK: questions and answers

Is there a version of K-9 Mail for older Android phones?

The current version needs Android 6.0 or later. Version 16.1 is the newest listed build that installs on Android 5.0 and later. Get version 16.1 · All versions

Can I install this APK over the version I already have?

Yes, if your installed copy is older. It is signed like the Google Play version, so Android installs it as an update and keeps your data.

Is K-9 Mail free?

The APK is free to download, but the app offers in-app purchases through Google Play.

Is the K-9 Mail APK safe?

No one can promise that a file is safe, but some things can be checked. The source store rates this file Trusted. Its signature matches the Google Play version. It is signed with the same certificate as the 3 other versions checked. After downloading, check that the file's MD5 is fd545de4769a447e7b2ebb4ab338af7e.