K-9 Mail

Name: K-9 Mail
Availability: InStock
Rating: 3.759999990463257 (99756 reviews)
Author: Mozilla Thunderbird

Mozilla Thunderbird

In-app purchases

99.8K reviews

PEGI 3

5M+

Downloads

PEGI 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

Oct 6, 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

Simi Winiker

July 27, 2021

Bring the old navigation back. Please! That was the main reason, we all used k-9 and not the rest of the pack. But like that it is degraded to be just another average mail client among many others, with little arguments to set itself apart. Truely disappointing. Now I have to look out for an alternative for something I used and loved (and recommended many, many times) for ages.

150 people found this review helpful

Dominik

July 26, 2021

Still no comment regarding the matter below, and now the new interface has rendered the app useless... Sorry guys, this update is just bad. Comment from 2019: My poll frequency is set to 15 minutes for every single mail account and all kind of notifications are enabled. Unfortunately, more and more often mails aren't shown for at least two hours, which is a no-go for a mail app...

27 people found this review helpful

Dan Lapetina

September 11, 2026

K-9 Mail is an excellent email application. Transitioning from a Samsung device to a Google Pixel and initially relying on Gmail was a significant adjustment. While there is nothing inherently wrong with Gmail, it contains far too many convoluted features that do not suit my requirements. I explored numerous alternatives, but none offered the straightforward functionality I was seeking. it's free, but I gladly donated.

2 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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PEGI 3

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