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Thunderbird for Android / K-9 Mail: April Progress Report

6 responses

We’re back with another progress report as we continue improving K-9 Mail for its transformation to Thunderbird for Android! We spent most of the previous month preparing for a new stable release. In April 2023, we finally published K-9 Mail 6.600.

(By the way, if you missed the exciting news last summer, K-9 Mail is now part of the Thunderbird family, and we’re working steadily on transforming it into Thunderbird for Android. If you want to learn more, check out our Android roadmap, this blog post, and this FAQ.)

K-9 Mail 6.600

Along with a couple of new features, a lot of changes and bug fixes went into the new K-9 Mail version. However, space for release notes in app stores is very limited. So we went with this list of changes:

Missing home screen widgets

After learning that an old bug in Android had finally been fixed in 2021, we changed the app to disable home screen widgets by default and only enable them after the user had added at least one account to K-9 Mail.
Of course we limited this to Android versions that should include the fix. However, this didn’t quite work as intended and existing home screen widgets disappeared on some devices. So we reverted the change in K-9 Mail 6.601.

K-9 Mail 6.7xx

With the stable release out the door, it was time for a new series of beta releases to test early versions of features and fixes that should go into the next stable release.

Bug fixes

The first beta version (6.700) didn’t include any new features, but fixes quite a few bugs (mostly obscure crashes).

IMAP ID extension

The GitHub user wh201906 contributed code to add support for the IMAP ID extension (thank you). It is used by an email client to send information about itself to the IMAP server. In turn, the server responds with some information about itself (name, software version, etc).

Unfortunately, some email providers reject clients not using this extension, even though the specification explicitly states the extension must not be used for that purpose. To make K-9 Mail work with such email providers without users having to change a setting, we decided to enable this functionality by default. Also, because we want to align our default values with Thunderbird, and it’s enabled there by default.

The information sent to the server is limited to just the app name – “K-9 Mail”. If you wish, you can disable this feature under Settings → <Account> → Fetching mail → Incoming server → Send client ID.

Next: Improved account setup

The main goal for the next stable release is to improve the account setup experience. Many new users are struggling with setting up an account in K-9 Mail. That’s because K-9 Mail only supports automatic account setup for a handful of large email providers. For all other email providers users have to manually enter the email server settings. And this can be a very frustrating experience.

Ideally, users only have to provide their email address and the app will figure out the rest. We’ll be adding support for Thunderbird’s Autoconfig mechanism which aims to deliver just this user experience.

Hopefully, we’ll be able to ship a first version of this in a beta release in May.


In April 2023 we published the following stable releases:

… and the following beta versions:

If you want to help shape future versions of the app, become a beta tester and provide feedback on new features while they are still in development.

6 responses

Reinhard Christeller wrote on

Most important is a spam filter.

Don Farnham wrote on

Will K-9 be able to link to Thunderbird, so that I don’t get all emails in both places ?

Jason Evangelho wrote on

Eventually yes! Once we introduce Thunderbird Sync.

Michelle wrote on

I’ve been considering buying an android tablet. Will this (K-9 mail) be what I would use for email instead of regular Thunderbird email if I do?
Thanks, Michelle

Jason Evangelho wrote on

Hi Michelle, Thunderbird for Android won’t be a feature-for-feature replacement for the more powerful desktop Thunderbird software, but it will be the best open-source option for Android! (And once Thunderbird Sync launches, keeping your Android and desktop versions of Thunderbird synced up will be easier)

Malle Eppie wrote on

Hi, I’ve been following the progress with great interest because on pc I use almost entirely Mozilla products. But on my phone, for mail, I use FairEmail by Marcel Bockhorst because of the build in security features like showing me which elements are blocked because they are trackers etc etc. How are you going to implement security in K-mail in a way I can see it working.? I mean I like to be informed about what is going on ; just deleting/stripping the non secure elements but not informing me is not doing it for me. Like I said, I would like to be informed.
Thank you very much in advance for your work on Thunderbird for Android.
Kind regards,
Malle Eppie

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