K-9 Mail is a communication app developed
by Mozilla Thunderbird.
The APK has been available since before 2010.
In the last 30 days, the app was downloaded
about 15 thousand times.
It's highly ranked.
It's rated 3.34 out of 5 stars, based on 95 thousand ratings.
The last update of the app was on May 8, 2025.
K-9 Mail has a content rating
"Everyone".
K-9 Mail has an APK download size of 10.78 MB and the latest version
available
is 10.0.
Designed for Android version 5.0+.
K-9 Mail is FREE to download.
Description
K-9 Mail is an open source email client that works with basically every email provider.
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★★★★★
Best replacement for stock telco/android email apps that start to have problems after a year or become bloated. Light, fast, dark mode and options under the hood (synching options + more). It works best for my personal email needs. You can set it to use "push" so you get mail quickly or use "fetch" on a schedule. [GMail is good as r many others, but I want an app for my personal stuff not accessible by corporations. Open Source!
★★★★★
It's a pity it isn't possible to create new e-mail folders, only move messages to existing ones. Apart from that, that's a great mobile e-mail client.
★★★★★
A Hidden Gem for PGP-Encrypted Email! K-9 Mail is an outstanding open-source email app, and its seamless integration with OpenKeychain makes it a must-have for anyone looking to send encrypted emails effortlessly. If you're searching for an easy way to create and use PGP encryption, this app makes it incredibly simple—just pull in your key from OpenKeychain and start sending secure emails right away. No complicated setup, no headaches—just secure, private communication made easy.
★★☆☆☆
Hi, Every time I'm trying to send an email with or without an attached document, it won't be sent but instead end up in the outbox. What should I do? Because I've used another app and that one gives me the same result but tells me that my email has been classified as spam by my email provider, so I believe this has something to do with my emails considered to be spams by K9 mail though they're not because when I send emails through my regular email client it works just fine. Thanks
★★☆☆☆
Personally, I have a problem with widgets that don't have a dark mode option. In general, I agree with others, the email homepage should have some kind of toggle to switch accounts (like gmail and outlook).
★★☆☆☆
I wanted to like this app, but I don't. It does not sync emails despite my global settings. Have to constantly refresh manually to download messages. The layout is okay, I like the unified inbox, but that's about it. I have to constantly tell it to show remote images and/or download complete message manually, as I have not been able to locate a global setting for this. It's a pain. Going back to Mozilla Thunderbird. UPDATE: Thx for Dev response. Did all that prior to review. Still doesn't work.
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