add "apply junk filter to moved entries" feature

[nobswolf]

After filtering out messages, I often have junk in my junk folder that is not marked as junk anymore. As it seems, the automatic application of the junk filter only works directly while polling the server but not when moving messages. So it would be nice to apply the junk filter on just moved messages.
Thunderbird itself has this option only in the menu, but not as a button. And scanning a whole folder takes very long.
I think a folder option "apply junk filter to moved messages" would be a pleasant feature.

[RealRaven2000]

Not really sure whether this fits into my Add-on description, certainly a very specific request. I wonder - should this not be done by some filter instead...

[nobswolf]

The problem is: I cannot find any point in Thunderbird where I can start "apply filter" but manually in the menu. There is no filter-rule available, and also no button, BTW.

Maybe you are right, and this is too specific. The messages are sorted out on my IMAP server. But somehow Thunderbird "remembers" them. And every message is checked only once for junk. And on the other hand, this "remembering" does not include the junk status itself.

[RealRaven2000]

The problem is: I cannot find any point in Thunderbird where I can start "apply filter" but manually in the menu. There is no filter-rule available, and also no button, BTW.

So yes there is a manual way of applying (all) filters from the menu - or if you want a dedicated button, use my Add-on quickFilters and then you can configure it to have a dedicated button (apply filters to selected mail) on the current folder toolbar:

Maybe you are right, and this is too specific. The messages are sorted out on my IMAP server. But somehow Thunderbird "remembers" them. And every message is checked only once for junk.

I think the internal Junk check (using Thunderbird's heuristics, so it's purely client side) happens to incoming emails that arrive in the Inbox. In your case, the mail server has done the work already and syncs the mail directly into your IMAP Junk folder?

And on the other hand, this "remembering" does not include the junk status itself.

I hear you. I wasn't sure about whether the Junk status flag was something that was defined by an email standard, so I asked ChatGPT - here is its answer:

There is no mail standard that defines a universal “junk” status.

• Spam/Junk is not defined by an RFC header. Headers like X-Spam-Status, X-Spam-Flag, etc. are non-standard and advisory, added by spam filters.
• IMAP also does not define a per-message junk flag.
• What is standardized (RFC 6154) is a special-use Junk mailbox (\Junk).

In practice:

• If an IMAP server moves a message into a folder marked \Junk, Thunderbird infers the message is junk based on the folder, not a header.
• Junk state round-tripping is server/client specific and not guaranteed.

So yes: folder context is authoritative, while X-Spam-* headers are useful hints and may become useful for filtering or heuristics later, but they are not a standard source of truth.

[RealRaven2000]

So my idea for you if you want to trust the junk flag from your server and want it to propagate into the Thunderbird junk mail status would be to try crafting a filter rule like

If X-Spam-Status contains Yes → mark as Junk

You would still have to run (all filters) manually on the Junk folder regularly. I would put the rule on top of the filters list and then add the actions stop filtering - to avoid fishing out other mails with your regular filters.

you could then run the filters from junk manually (but you wouldn't have to select the mails beforehand):