K-9 Mail

Name: K-9 Mail
Availability: InStock
Rating: 3.0118110179901123 (99871 reviews)
Author: Mozilla Thunderbird

Mozilla Thunderbird

In-app purchases

3.0

99.9K 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.

Updated on

Jun 4, 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

Review by Kelson Vibber on August 19, 2023

Kelson Vibber

No frills, no ads, no tracking. K-9 stays out of your way and lets you read/write/organize your email across multiple accounts plus a unified inbox. Easy to set up with IMAP or Gmail. Works well with both light and dark mode, and you can switch modes per message when needed. Optional 2-column layout works great for tablet screens in landscape mode (and can be set to auto-switch based on screen orientation).

31 people found this review helpful

3.0

94.6K reviews

Rick Steeves

March 22, 2026

I've been using K-9 for years, and overall its feature set is exactly what I want. However recently, I presume after the most recent update, it's regularly crashing. either hitting reply, or launching it as one of the edits to share something. it's not so bad it's unusable, but I'm spending a lot of time doing things twice. which is a shame for something that's always been so solid in the past

5 people found this review helpful

Mozilla Thunderbird

March 23, 2026

Thanks for letting us know about these crashes! If these are still happening, can you report them to our bug triage team and developers at https://github.com/thunderbird/thunderbird-android/issues/ so they can investigate what's going on and try and fix it? We want the app to be solid for you too!

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.

38 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.

63 people found this review helpful