Are you saying that the setting "filter before junk classification" is not working?

No, I'm not saying that. Ex: filter A moves all emails with sender S to folder F, before junk classification (& move to junk folder). But when I open folder F, junk classifications is triggered, and move junk-classified emails to the junk folder. I wish to suppress this behavior, and keep this move-to-junk-folder only for INBOX.

another dissatisfied Yahoo customer perhaps? Their junk filter works on all folders on access, Thunderbird's does not.

Nope, nothing to do with yahoo, it's a private imap server. When opening folder F, I can see before my eyes emails being classified as junk by thunderbird, then disappear, to be found in the junk directory. I wish this behavior disabled for folders other than INBOX.

Please post a copy of your spam folder, showing some of these emails.

I have 50 emails in my gmail spam folder. One of them was put there by Thunderbird. However there are plenty of "security" products that think you need protection from spam and scams and many of them are not very reliable. So even have Thunderbird addons that don't work very well.

What mail server are your using? If it is a private IMAP server, what mail server software is being used.

Those are spam emails, I do not really see how it can be relevant to see them. My question remains simple: how to configure thunderbird to "Move new junk messages to: junk folder" *only* for INBOX folder (ideally, on a per folder basis). I do not have access to the imap server version, and do not see how it's relevant to this thunderbird's behavior. My thunderbird has no add-on.

re: I do not have access to the imap server version, So, the account is a POP account.

On my pop accounts: All emails incoming to Inbox because it is POP. Some get filtered before junk controls to other folders like you. All good contacts are in address books set up as whitelisted so none of those emails go to Junk. I do not allow junk mail headers to be used by Thunderbird, otherwise any email set with a Spam rating by the server spamfilters may end up in Junk automatically.

Is 'sender S' someone in one of your address books? If no: add as contact to address book

Check settings: In 'Account Settings' > 'Junk Settings' Is this checkbox selected : 'Enable adaptive junk mail controls for this account' If no then select it.

Are your address books selected as a whitelist ? If no then select the address books.

Have you selected the checkbox 'Trust junk mail headers.....' ? If yes, then uncheck it.

Please confirm set up.

So, the account is a POP account. No, I access my emails on this server using the IMAP protocol, connecting to an IMAP server. Not having its version does not make it a pop3 server... Geez... Making false assumptions and not addressing my specific question does not help. My question is: how to stop thunderbird from moving junk emails out of folders other than INBOX.

What are all the Junk Settings you have set up for that account ? They are still relevant. Please supply info or just post an image of settings.

Also, as this is an imap account, the server spam filters could have put the emails into the Spam folder which synchronises with server. That is unknown at his point.

re:My question is: how to stop thunderbird from moving junk emails out of folders other than INBOX. At this point we do not know it is Thunderbird, because we do not know your Junk Settings and as you are using IMAP that means the server maybe overruling Thunderbird which is a very common issue with Imap accounts.

Thunderbird only auto uses Message Filters on the Inbox regardless of whether it is pop or imap. Any manual selection of Junk will use the Spam/Junk folder.

Please tell us the Junk Settings.

Here are 2 screenshots: the big one is junk settings for this IMAP account, smaller one is global junk preferences. The server spam filter flags some of the spams (it's quite conservative, some spams go through), but does not move them by itself. Messages marked as spam by this spam daemon are moved to a specific folder by sieve commands. The junk messages I am concerned with are not flagged as SPAM by this spam daemon on the imap server. I repeat what I wrote before: opening with thunderbird a folder where were moved messages (not flagged as spam by the imap spam filter) "I can see before my eyes emails being classified as junk by thunderbird, then disappear, to be found in the junk directory. " As a test, I even first opened this folder with another email client (alpine), saw the new messages sitting there. Only when I opened this same folder with thunderbird did I see those messages disappear. So I do not see what else than thunderbird could be moving those messages.

Well open the log and lets see those emails in folders other than the inbox being identified as junk and moved.

I also suggest you open the more troubleshooting information on the help menu and post the content to a reply in the forum (it has a copy to clipboad button to facilitate this)

Thunderbird does not to anyone's knowledge move mail from any folder other than the inbox as Spam/Junk. Logically if that is happening then there is either a bug, which affects only you out of some 20 million users, or there is something on your system causing this issue.

So instead of continuing to complain that no one is answering your question. Be aware we are trying to investigate why. Because no one else has ever seen this happen or heard of it, except in terms of rogue security software and addons.

Personally I have just seen you have disabled junk filtering, so am only looking for an external cause. Thunderbird is not doing this, despite the evidence of your eyes. Just like those that complain Thunderbird is deleting their mail because they deleted it on their phone and the deletion synchronized. I feel something similar is happening here. I asked you about the server. the least you could advise if the server name, we can then test it and see if it has issues. But you said it was a private server, that implies it is on site with you. I do not doubt you see something occurring, but the cause is entirely unknown.

OK, so you do not have Junk Controls enabled on that imap account. You just have the settings set for what to do if you select an email as Junk.

In the first image it mentions a Global option to 'Enable adaptive junk filter logging' Please click on 'Show log' and post image of contents.

Do you have any Message Filters which you created that have an action to set junk status as junk OR move to Junk?

Do you see any mention of move to junk in the 'Tools' > 'Activity Manager'? Please post image showing any mention of movement.