K-9 Mail

Name: K-9 Mail
Availability: InStock
Rating: 3.118811845779419 (99669 reviews)
Author: Mozilla Thunderbird

Mozilla Thunderbird

In-app purchases

99,7K reviews

PEGI 3

5M+

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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

10 Nov 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

John Dowdeswell

29 July 2021

Forced to update the other day which came as a surprise after a stable release for years. It worked for about two days having automatically imported all my account settings from the old version , albeit with a slightly strange user interface, and now when I start the app, it wants me to create or import new accounts, with no way to skip. So I don't know where all my accounts have gone. Absolute rubbish. I'm so angry. Will have to start looking for a new email client.

49 people found this review helpful

Tom Hindley

30 August 2021

Disappointing. Older version was fine, and no doubt worked for most users. If it isn't broken, don't try to "fix" it. When refreshing all folders, it causes the app to crash each time. Resetting and preventing such crashes (best achieved by uninstalling, i suspect) mean it's faster to to ask my Postie with a limp to deliver printed emails! Waste of space app now. Used to be great, no longer.

47 people found this review helpful

Phil C

27 July 2021

K9 user for many years, it been the best open source mail client. But this new UI overhaul is as bad as it gets. I wonder the developers asked themselves the question "can I do all the things with the new UI, I can do with the old" if answer is no, then it's probably not the right change. Things that are now missing, accounts overview which provided easy access to filtering, filtering by starred, filtering by unread, all messages view. Thumb friendly Navigation at bottom. It's time to fork it.

40 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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