K-9 Mail v16.1
APK · 13.4 MB · version code 39033 · Android 5.0+ · uploaded Apr 20, 2026
- Signature matches the Google Play version Details
Quick check before downloading
Answer this to unlock the download. It keeps automated downloaders away.
Compared with the latest version
The latest version is v24.0, uploaded Oct 7, 2026 — about 6 months after this one.
- Size: this file is 13.4 MB; the latest is 10.9 MB (2.5 MB smaller).
- Android: this version needs Android 5.0+; the latest needs Android 6.0+. Use this one if your device runs an older Android release.
- Both versions request the same permissions.
File information
- Version
- v16.1 (39033)
- Uploaded
- Apr 20, 2026
- Size
- 13.4 MB
- Requires
- Android 5.0+ (API 21)
- CPU support
- x86 32-bit, x86 64-bit, ARM 32-bit, ARM 64-bit
- Screen
- Small screens and larger
- MD5
- b0cff138b8ce30e122045ec249fa4b70
- Signing certificate (SHA-1)
- 0F:1F:32:52:CB:A1:C9:4D:DD:61:86:DA:D5:A0:35:E9:6C:6E:E5:E3
- Signed by
- CN=Jesse Vincent, OU=Open Source Labs, O=fsck.com, L=Somerville, ST=MA, C=US
- File name
- com-fsck-k9-39033-74422359-b0cff138b8ce30e122045ec249fa4b70.apk
- Package
- com.fsck.k9
- Downloads (all versions)
- 5M+
- Age rating
- PEGI 3 · Everyone
What's new in v16.1
- Default sync interval changed to 15 minutes
- Use application icon in push notification messages
- 'Colorize contact pictures' default changed unexpectedly from true to false
- Displaying IMAP password in did not prompt for authentication
- Sync debug logger did not write any logs
Permissions (16)
This version 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
Security & authenticity
Security rating: Trusted
Signing certificate
- Signature matches the Google Play version Checked by the source store on Apr 20, 2026.
- Certificate issued to “fsck.com” This is the certificate of the Google Play version.
- Same certificate as the 6 other versions checked
Store checks
- Developer signature not checked yet Apr 20, 2026
- Validated against Google Play Apr 20, 2026
- Uploaded by “appupdater” Gold tier · 117,810 followers · uploading since 2020
Scans come from the source store; the certificate comparisons are AAPKs's own, made from the files' published signatures (6 other versions compared). AAPKs doesn't scan files itself.
How to install K-9 Mail on Android 5.0+
You'll need about 26.7 MB of free space.
- Download the APK — tap Download APK above (13.4 MB). Chrome shows “File might be harmful” for every APK file; choose Download anyway only if you trust this file.
- Open the file — tap the download notification, or open Files › Downloads and tap com-fsck-k9-39033-74422359-b0cff138b8ce30e122045ec249fa4b70.apk.
- Allow the install (first time only) — Android 8 and later asks for permission the first time an app opens an APK: tap Settings in the prompt, turn on Allow from this source, then go back. Manual path: Settings › Apps › Special app access › Install unknown apps (on Samsung: Settings › Apps › ⋮ › Special access). On Android 7 and older: Settings › Security › Unknown sources.
- Check the file (optional) — the MD5 of the downloaded file should be b0cff138b8ce30e122045ec249fa4b70. If it differs, the file is damaged or was changed: delete it and download again.
- Tap Install — Android asks “Do you want to install this app?”. If Google Play Protect shows a warning, read it before you continue: the source store rated this file Trusted, but only install apps from sources you trust. If an earlier version is installed, this one only installs as an update when it is signed with the same certificate (SHA-1 shown above).
- Open K-9 Mail — tap Open on the install screen, or find it in your app drawer.
Common install problems
- “App not installed” — a version signed with a different certificate, or a newer version, is already installed (Android doesn't allow downgrades). Uninstall it first; back up your data, because uninstalling deletes it.
- “There was a problem parsing the package” — the file is incomplete, or your Android is too old (this version needs Android 5.0+). Download it again, or pick an older version.
- “App not compatible with your device” — this build contains native code for x86 32-bit, x86 64-bit, ARM 32-bit, ARM 64-bit only. Devices with other processors can't install it.
- Blocked by Play Protect — Play Protect checks apps from outside the Play Store. Only continue if you trust the source.