K-9 Mail
![]() | |
Original author(s) | Jesse Vincent |
---|---|
Developer(s) | MZLA Technologies Corporation, Christian Ketterer |
Initial release | 27 October 2008 |
Stable release | 8.2
/ 10 December 2024 |
Repository | |
Written in | Java, Kotlin |
Operating system | Android |
Type | Email application |
License | Apache License 2.0 |
Website | k9mail |
K-9 Mail is a free and open source email client for Android. It is designed as an alternative to the stock email clients included with the platform; it supports both POP3 and IMAP protocols and supports IMAP IDLE for real-time notifications. The project is named after the Doctor Who character K9.[1]
For end users, K-9 Mail started to transition towards becoming Thunderbird for Android in October 2024.[2][3]

History
[edit]The source code was first published to its git repository on October 27, 2008[4] by Jesse Vincent and the first binaries were released to the public on the Google Code site the same month.[5]
In 2015 the project received $86,000 of funding from the Open Technology Fund.[6]
On 13 June 2022, it was announced that K-9 Mail had been taken over by MZLA Technologies Corporation, a subsidiary of the Mozilla Foundation with current maintainer Christian Ketterer joining the team, and plans for K-9 Mail to be rebranded as Thunderbird for Android following the completion of a feature roadmap, including sync with Thunderbird on PC, integrating Thunderbird's automated account setup system, message filtering, and improvements to folders.[7]
On 30 October 2024, the first stable release of Thunderbird for Android (Thunderbird Mobile) was launched as version 8.0.[3] Thunderbird for Android can be installed via Google Play and F-Droid, among others.[8] The Thunderbird team had planned in 2022 to maintain K-9 for one year after the release of Thunderbird Mobile, i.e. until roughly October 2025.[9]
On 6 May 2025, the stable version 10 of Thunderbird Mobile and the beta of version 11 were released.[10]
Reception
[edit]In the early 2010s it was widely reviewed, and was particularly praised in the media between 2011 and 2013 as a replacement for the default mail application.[11][12] At the time, it was a leading alternative Android app, often recommended[13] when a user did not want to use the default app. It was awarded the "Best App for Sending Email" in the 2010 "Best Android Apps" book.[14]
Features
[edit]- Works with IMAP, POP3
- Folder sync
- Encryption with OpenKeychain support
- Signatures
- SD card storage
See also
[edit]References
[edit]- ^ "About". Retrieved 1 February 2024.
- ^ Evangelho, Jason (2022-06-13). "Revealed: Our Plans For Thunderbird On Android". The Thunderbird Blog. Retrieved 2025-05-09.
- ^ a b Ayhens-Madon, Philipp Kewisch, Monica (2024-10-30). "Thunderbird for Android 8.0 Takes Flight". The Thunderbird Blog. Retrieved 2025-05-09.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ "k9mail/k-9". Github. Retrieved 1 September 2013.
- ^ "Downloads - k9mail - K-9 Mail is an advanced email client for Android - Google Project Hosting". Retrieved 2013-08-15.
- ^ Open Technology Fund. "Projects we support - K-9 Mail". Open Technology Fund Website. U.S. Agency for Global Media. Retrieved 2022-03-13.
- ^ Axon, Samuel (2022-06-13). "Email client K-9 Mail will become Thunderbird for Android". Ars Technica. Retrieved 2022-06-14.
- ^ "Thunderbird Mobile". Thunderbird. Retrieved 2025-05-09.
- ^ Evangelho, Jason (2022-06-13). "Frequently Asked Questions: Thunderbird Mobile and K-9 Mail". The Thunderbird Blog. Retrieved 2025-05-09.
- ^ "Releases · thunderbird/thunderbird-android". GitHub. Retrieved 2025-05-09.
- ^ Paul, Ryan (2011-01-24). "Excellent K-9 mail app for Android keeps your messages on a leash". Ars Technica. Retrieved 2013-08-15.
- ^ "K-9 Mail Receives First Significant Update In 9 Months - Improved Interface, Altered Widget, Bug Fixes, And More". Androidpolice.com. 2013-06-28. Retrieved 2013-08-15.
- ^ Begun, Daniel (2011). Amazing Android Apps for Dummies. Wiley. ISBN 9781118061428.
- ^ Hendrickson, Mike (2010). Best Android Apps. O'Reilly Media. p. 80. ISBN 9781449382551.
External links
[edit]- Official Website
- Github Development
- Wiki Page
- K-9 Mail on Google Play
- K-9 Mail Android package at the F-Droid repository