K-9 Mail

Mozilla Thunderbird

In-app purchases

99.8K reviews

Everyone

5M+

Downloads

Everyone

Users Interact

Learn more

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

Aug 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

94.5K reviews

Jessica Meyers

December 4, 2024

I loved K-9 before this update. But now it's so hard to distinguish between my accounts in the menu. Before, I'd given each one a different profile pic and color, so I always knew which account I was looking at. They also appeared in a set order, so I could navigate easily. Now 4 of my 5 accounts are labeled "GM," and the highlight color is the same for all 5. What?! AND each time I open an account, the list order shifts, so they're never in a predictable order! Wish there were a way to revert.

41 people found this review helpful

Mozilla Thunderbird

December 4, 2024

Thanks for your feedback and we're sorry for any frustration over account icons and management. Improvements are coming in the 8.2 release to the current account initials. You can also help us test this and other changes in the K-9 Mail Beta. We hope this and future changes improve your experience!

Phillip Honstein (Phillip H)

December 5, 2023

Customizable, schedulable, sane, private. Handles multiple accounts, makes it easy to switch between accounts, has a unified Inbox to display all messages together, doesn't advertise to me, and displays all messages perfectly. It's just an email client, and a very good one. I didn't start using it until the Thunderbird folks took it over, and I wish I had tried it sooner.

65 people found this review helpful

Mik Bel

June 17, 2024

It crashed many times during setup. Can't get passed setup. Edited: After numerous attempts I identified the step at which the setup was crashing. After typing the password to log into my email account, making the PW visible would crash the app. Finally, I set it up. Nice app, simple, not many bells and whistles, works well with Google, Microsoft.

27 people found this review helpful

What’s new

K-9 Mail version 22.0

New:
- Incognito Keyboard privacy setting
- Thundermail interim screen when adding account

Changed:
- Selected sort option now shows indicator in sort menu

Fixed:
- Messages could scroll horizontally when content fit screen
- Thread deletion confirmation incorrectly said only one message would be deleted
- Notification actions difficult to scroll/reorder on small screen
- Show Headers collapsed multi-line email headers into single line

Flag as inappropriate

Everyone

Users Interact

Learn more