Some read emails hidden from K9 only

Brave_New_World · November 5, 2026, 10:25pm

I am having an issue with some emails vanishing from the inbox on K9 after they have been read. I can literally see the email vanish from the inbox after viewing the email and going back to the inbox. The emails (and it is only some, not all of them) are not moved to junk/deleted and if I view the inbox using a different email client (eg outlook or thunderbird on a pc) the missing emails are still in the inbox. They just do not show up in the inbox in K9.

It is not a server issue since the missing emails are visible in other email clients. It is as if K9 is tagging them as junk but rather than moving them to the junk folder, K9 is just making them invisible (but only to K9).

Has anyone struck this before and can anyone suggest a way of stopping it from happening?

For the record, this is on my wife’s phone. K9 does not do this on mine, even though it has the same setup and is using the same ISP (but a different account).

Zeroid · November 6, 2026, 8:37am

Do you have sort by read/unread status selected?

An email will re-positioning below unread messages after reading it. A message can seem to disappear when not in the list position it was seen last.

Brave_New_World · November 8, 2026, 8:50pm

No, it’s not selected. And only some emails are affected. Others remain in the same place when going back to the inbox.

Zeroid · November 8, 2026, 11:07pm

What version of K9 and Android are you using?
Do you observe the issue only within Unified inbox, the accounts inbox or both?

I’m not able to replicate the issue however there is an old github ticket reporting a similar issue.
You could add your experience to this report.

github.com/thunderbird/thunderbird-android

Read emails disappear from view

opened 07:06PM - 19 Nov 24 UTC

JanCeuleers

unconfirmed

### Checklist - [x] I have used the search function to see if someone else has …already submitted the same bug report. - [x] I will describe the problem with as much detail as possible. ### App K-9 Mail ### App version 8.1 ### Where did you get the app from? Google Play ### Android version 14 ### Device model Nokia X10 ### Steps to reproduce 1. Open inbox which contains at least one unread email 2. Open an unread email 3. Return to the inbox (e.g. using the swipe-from-right-edge gesture) 4. Observe that the email that was just read no longer appears in the inbox 5. Attempt to make the missing email re-appear by refreshing the inbox (swipe from top). Not effective: the email in question remains invisible. 6. Navigate to another folder, e.g. Sent 7. Return once again to the inbox 8. Observe that the previously missing email is now visible once again (meaning: it had not been deleted, it was merely not being displayed) ### Expected behavior Emails that have already been read should remain in the inbox and be visible there. Only markup should set them apart from unread emails: on my phone unread emails appear in bold whereas read emails appear in regular text. ### Actual behavior Read emails are not visible in the inbox until the inbox is navigated away from and then returned to, as described above. ### Logs Your instructions for retrieving logs state that they are about Thunderbird for Android; it is not clear whether they also apply to K9. If so let me know and I will endeavour to provide logs.

Brave_New_World · November 10, 2026, 9:12am

The latest versions of android & K9. It’s using the unified inbox, but the person in question only has one account. The issue also appears in the account’s inbox in K9.

I was also unable to replicate it on my android phone.

It could be the same issue you mentioned from 2024. I’ll add a me2 to that, although since K9 is being absorbed into thunderbird and it does appear to be a very rare issue, I doubt there will be any action on it. At least I know I’m not imagining things. The use has gone back to using outlook for android) which does not ‘eat’ the emails in question. I tried outlook (android), t’bird (windows) and even webmail and the missing emails all show up, it’s just K9 that’s hiding them. And I couldn’t see any setting that would have a bearing on it. I’ve posted to the t’bird reddit forum and no-one there has a clue either.