Folder polling is not reliable any more

[cremor]

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App version

6.803 (still happening with Thunderbird for Android 16.1)

Where did you get the app from?

Google Play

Android version

14 (still happening with 16)

Device model

Pixel 7a

Steps to reproduce

1. Configure the app to poll for new emails every 15 minutes.
2. Turn off the phone screen and do not use the phone.
3. Send yourself an email from another device.
4. Wait for the notification.

Expected behavior

Notifications for new emails should be shown not more than 15 minutes later.

Actual behavior

No notifications for new emails are shown. As far I can tell it's not just that the notification is missing, but the app doesn't even poll for emails.

Sometimes I get the emails when I wake up the phone (turn the screen on).
Sometimes I need to unlock the phone to get them.
Sometimes I even need to open the app. In those cases I see that no new emails are shown, then the progress indicator line on top of the email list shows up, and only then the emails are polled.

This problem started a few weeks ago. Maybe with the update to version 6.802. Maybe it was also an Android update (e.g. April or May update) that caused it.

The Android setting/permission for battery usage of the app is already set to "allow background usage" and "not limited" (my translations, I'm not sure on the official english wording of those settings).

Logs

No response

I don't know if this is related, but folder syncing seems unreliable too : I've deleted a lot of emails from Thunderbird (Linux), changes appears on the email provider web interface, but I still see deleted emails on K9 (Android 13, v6.803, F-Droid)...

[Xavron]

There's actually a lot of possibilities here and some are device.

• Android 14 for instance also has a separated location of sleeping and deep sleeping apps. The issue post here doesn't specify.

• Android also has various things at play including for example attempts at forcing apps to not run on exact time as it uses more battery by keeping the device from deep sleep.

• Android manufacturers can at times be overly aggressive and kill background apps no matter what you do.

• The email service that is used may timeout or have other connection issues or limits causing it to not be on exact time or not happen.

• Apps can do things like wake locks but even that is receiving some force blocks by Android so not all situations will work.

Its difficult to say what the app can or can't do in being exact and there will be cases where it may not be possible. Conversely, Google won't really allow this to happen to their own app which is another thing entirely lol.

But, all 3rd party developer Android apps are going through this. Some get by better but many see this type of problem.

[cremor]

• Android 14 for instance also has a separated location of sleeping and deep sleeping apps. The issue post here doesn't specify.

Where can I find both of those settings?

• The email service that is used may timeout or have other connection issues or limits causing it to not be on exact time or not happen.

I use 3 email addresses of 2 different providers (one is Gmail). All show the same problem.

[Xavron]

The Android 14 new feature should be in Android Settings > Battery > Background usage limits > sleeping / deep sleeping apps. Android 14 will auto add apps as time goes by. If its the one you were talking about then not allowing it in there is a good idea as it definitely can and will break apps.

[cremor]

I don't have such an menu entry in the battery settings. I've also looked through all sub-menus and could only find the app specific settings which are already set to unrestricted background usage.

[Xavron]

It could be at a different location in Android settings on that device. Perhaps do a settings search for it?

[cremor]

Searching the settings menu for "background", "sleep", "standby" etc. doesn't bring up anything. But that doesn't say much, because there is for sure a "allow background usage" setting (that I have already turned on, as written in the initial post). So that search function seems useless.
I've also searched the settings manually and couldn't find anything that I haven't already set to allow anything for K-9.

[w6a8w8]

I'm encountering a similar issue on Android 12. I have polling set to every 2 hours for two different accounts, with background activity and autostart fully allowed. Despite these settings, I often miss notifications for new emails. Even after opening the app, emails don't sync automatically—I have to manually pull down to refresh. Sometimes emails received over 4 hours prior aren't displayed until I do this, suggesting that sync fails at least twice in a row. Any insights or fixes would be appreciated.

[rienheuver]

I'm running into this as well. Oneplus 9 with original OS. I just synced by manually pulling down in the app and it fetched mails from over 24h ago. My interval is set to 15min.

[cremor]

This problem still exists in Thunderbird for Android 16.1 with Android 16. I've updated the initial report to show this.

[iamtalhaasghar]

Wasnt an issue at all but since few days (or weeks) it started happening with me as well.
Version: 16.1

Edit: Dont optimize background usage is already on for K9 on my phone.