Have you considered that most folks, so I am assuming you, use IMAP and that is synchronised to the server where your providers "junk grabber" is doing this. I actually recommend you turn of the junk filter in Thunderbird. Just to determine if you issue is local or something your provider is doing.

Added to that many third party antivirus product come with spam and scam filtering that also messes up on a fairly regular basis and put the wrong things in the junk folder. When the antivirus messes up though it is usually everything goes into the junk folder.

Please report your results.

I have 5 email accounts they were all working for years. One day, one of the accounts started sending EVERYTHING to the "JUNK" folder. I have no idea why. The other 4 accounts are working fine.

I've been through settings many times and compared those setting to one of the working accounts. Can't see the problem

Any ideas?

Thanks

What mail provider? You say one of the five. Are they all provided by the same mail provider. Or is the troublesome one offered by say Yahoo and the others by gmail.

Is the troublesome on IMAP and the others POP?

Once thing you need to accept early, if the person is in your address book and that address book is selected in the account settings as containing trusted addresses Thunderbird never places mail from those addresses into spam. See https://support.mozilla.org/en-US/kb/thunderbird-and-junk-spam-messages#w_whitelisting

Just because you see the issue you are describing appear in Thunderbird that is not necessarily where the issue lies. Actually it is rarely where the issue lies. Most folk these days have IMAP mail accounts and therefore their mail is synchronized to the mail server. This means if your mail provider comes up with hair brained definition of SPAM, then suddenly Thunderbird will demonstrate exactly that by virtue of Synchronization. I mentioned Yahoo above, but Outlook likewise does not offer you a way to opt out of their definitions and actions regarding spam either. Likewise of you have a phone app that does something odd (some delete mail very quickly to save space on cheaper phones with limited storage) and we see folk here complaining that Thunderbird is deleting their mail. We also see regularly folk complaining that all their mail goes to spam instead of their inbox. Historically this have been a function of antivirus products that fancy themselves as SPAM or SCAM managers. But the nuances can be difficult because most folk these days own laptops with Wifi internet and that make most diagnostics difficult. They are cheap and cheerful for a reason.

So yes I see the problem, but I am looking at a very large picture. Much larger than the one I think you are looking at, where you are seeking a solution within Thunderbird for a problem that has not yet been more than blamed on Thunderbird for an account that I know nothing about at all. Perhaps you might share enough information that I can stop guessing about what providers you use and what antivirus etc. BTW if you say McAfee or Norton I will just tell you to uninstall them and see if the problem goes away. I am done fighting with those two products. I see them as being as insidious as the threat they purport to protect from.

Steve Powell,

Have you sorted out your problem?