K-9 Mail

Name: K-9 Mail
Availability: InStock
Rating: 3.3487331867218018 (99968 reviews)
Author: Mozilla Thunderbird

Mozilla Thunderbird

In-app purchases

3.3

100K reviews

5M+

Downloads

USK: All ages

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

Oct 20, 2025

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

3.3

94.7K reviews

Jared Reid

July 18, 2025

the app is okay, though I'm not a fan of the way the unified inbox is sorted, like it isn't the top heading in a folder with multiple inboxes. it's not intuitive. and, what about unified spam, trash, and draft folders? good UI and it works well enough without ads on your face.

18 people found this review helpful

Mozilla Thunderbird

July 18, 2025

Thanks for your review! We're responding to feedback like yours, and our upcoming changes to the account drawer will also include a better experience for the Unified Inbox and other unified folders. You can read more and see screenshots in the Juny Mobile Progress Report at blog.thunderbird.net!

Marco B

November 14, 2021

Failed redesign, now i can just use any other mail app. Setup for accounts is easier in other apps, since they detect settings by themselves. I used to choose K9 for monitoring several email accounts. It's a real hassle if you got a few accounts and don't want to use a unified inbox. So instead of just glimpsing on my private accounts and see if they got anything, i have to go through them all. Especially business mail accounts receive more mail, so you have to scroll down and down and down :(

66 people found this review helpful

Johannes Garz

January 8, 2025

Free and open source, but still comes with a great design. Also has push notifications, swipe actions, folder customization and a dark theme. I never had any issues with the synchronization of 6 different accounts (Gmail & self-hosted). Only thing I'm missing is the option to customize the quick actions on a notification, I'd like to be able to archive a mail right from there.

20 people found this review helpful