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OK, so I see where others Thunderbird users have previously asked about why e-mails are disappearing from their Thunderbird junk folder but have a quite different problem. So, when I go to my junk folder momentarily all the mails are present, but then right before my eyes 2 or 3 just simply disappear! They truly disappear and are nowhere in any folder on Thunderbird account -trash, archives, sent, etc. I did the obvious and Googled and there are some informative posts about Thunderbird settings for time-outs and filters and automatic deletion - BUT, BIG BUT all my settings conform already to all their suggestions on these various web posts. So at my wits end I ask the folks in the community if they have any explanation as to why e-mails in junk folder on Thunderbird literally just disappear in front of me. I would be greatly appreciative of any suggestions.

Since yesterday (27 Apr 2026) any and all mail that comes into Thunderbird gets marked as SPAM. I searched online and found people saying that I could reset the junk training filter, so I did this, but incoming mail was still marked as spam. The next suggestion was to delete the training.dat file. Did that, restarted Thunderbird and incoming messages are still marked as spam. The last suggestion was to turn off adaptive junk mail controls. Didn't want to do that because I assumed that it would let spam through. Nope. Turned it off, restarted Thunderbird and two emails from my work came in and got flagged.

I'm running version 140.10.0esr (64-bit) on Windows 11. I am using IMAP to connect to the mail server but it's not running any spam detection software (like Spamassassin). I know this because it's my server and even if it was, no updates have been preformed since the first of this month and this just started happening yesterday. Combine this with the bug that Thunderbird notifies me of incoming mail, even if it's spam (didn't post about this because there are plenty going back a couple of years), is starting to make me look for an alternative.

I'm concerned I've got my Junk set up so that TB is not actually learning what is spam, plus spam is not easy to delete.

First question. What is putting [SPAM] in headers before emails arrive? Is it SpamAssassin? I use my own website/email address and my host uses Spam Assassin. My host in addition has their own native Bayesian spam, but that would use *****SPAM***** headers and I never get these.

The problem is this. Most junk arrives marked [SPAM] but doesn't go in the Junk folder, which is the only folder with one-click Empty Junk. So I have filters set up to direct headers with [SPAM] in into the Junk folder.

(i) the [SPAM] arrives in the Junk folder not marked as Junk even though the filters are carefully set up to "Set Junk status to: Junk"

(ii) it doesn't seem possible to bulk mark the contents of the Junk folder as Junk. If I click the flame icon in the header row once, then all the flame icons are switched to not-Junk as expected. But if I click it again then only some, not all, are changed back to Junk. IE completely different from normal all-off/all-on conventions.

(ii) some [SPAM] ends up in the Spam folder despite the filters. This looks like pure filter failure.

The goal is the get all the [SPAM] messages in the Junk folder along with the Junk the TB itself puts there, so (a) I can delete them with a single click plus (b) all marked as Junk so the TB is learning from the [SPAM] emails.

How can I do that please? What am I doing wrong?

Many thanks.

When I click "Empty Trash," the trash is emptied. However, the status indicator (number of emails) remains unchanged until I click the trash icon again. Is there a missing "Refresh" function?