So, it’s been a while since posting this and I still don’t see any change in the public Junk folder… I can’t delete it, unless i do it manually but it keep re-appearing, or when I run the cron manually…
I think that the Junk public folder can be our friend. Apart from disappearing and reappearing (due to this fix) it also collects mid-score spam messages from any other public mail folder.
Those messages are likely to be spam, but their score is not so high to decide they can be rejected during the SMTP transaction.
So it could be wise that somebody can subscribe that folder to check if some false-positive lands on it.
My proposal is to treat the “Junk” public mail folder like any other public folder. For privacy reasons, people authorized to see it should be authorized to see any other public folder contents.