K-9 Mail

Name: K-9 Mail
Availability: InStock
Rating: 3.307692289352417 (99669 reviews)
Author: Mozilla Thunderbird

Mozilla Thunderbird

In-app purchases

99.7K reviews

Rated for 3+

5M+

Downloads

Rated for 3+

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About this app

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.

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

Updated on

Nov 11, 2026

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.

No data shared with third parties
Learn more about how developers declare sharing
No data collected
Learn more about how developers declare collection
Data is encrypted in transit
Data can’t be deleted

Ratings and reviews

94.4K reviews

James Pike

July 28, 2021

I especially miss the archive button showing up after selecting emails. Archiving multiple emails at a time was a common action for me, having to archive each email individually via several presses is very time consuming. I'm not sure if I can get used to the unified view, ATM I prefer the account view that was removed. I'm trying to give it a chance. I really hope the archive button will come back. This was a 4.5 star app for me, now it's more like a 2.

1 person found this review helpful

Don Mankewich (Don)

August 13, 2026

Fix for OnePlus (OxygenOS 14) notification loop & stalled IMAP Push: 1) App: Disable Push completely; switch to 15-min polling for all accounts. 2) Phone Battery: Set K9 to 'Auto-optimise' and leave 'Sleep Standby Optimisation' ON. 3) Phone Notifications: Keep account 'Miscellaneous' channels ON, but change to Silent and turn OFF Banners & Lock Screen. This stops background network freezing, eliminates the alarm permission nags, and allows new mail to chime normally on the lock screen.

2 people found this review helpful

Jack Lee

August 9, 2026

Setting "local folder size" has not been working, even with version 22. I set mine to 50 messages, but my Inbox has 2000 plus messages now. Pls fix. Real hassle to have to manually delete emails. Using this with a POP3 account. Used to work with previous versions. But not now.

3 people found this review helpful

What’s new

K-9 Mail version 24.0

New:
- Signatures support HTML
- Reply offers Reply or Reply All

Changed:
- Long account names fit in two lines

Fixed:
- Compose selection invisible in light theme
- Status icons unreadable when selecting messages
- Recipient expander failed to collapse after edit
- Camera attachments could crash the app
- Save All saved each attachment with same file content
- HTML signatures could disappear after rotation
- Edit as new used wrong identity for queued mail

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Rated for 3+

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