Junk is local to Thunderbird. I wouldn't expect this classification to propagate back to the server. Junk labels are not part of the RFCs that define how email works.

Your email provider might be labelling or categorizing them as Spam or Bulk, but that is totally independent and external to Thunderbird and its Junk Controls.

Are there any "funny" characters in the affected email addresses? Thunderbird filters seem to be blind to certain characters such as '+' and I wonder if this stops it from matching certain addresses.

Have a client with the same/similar problem.

The emails from one of here daughters (gmail address, which is in the addressbook', hence should be whitelisted to begin with) keep getting flagged as junk (with that "flame" icon) over and over again. If you unmark them as junk all at once, after a few minutes or any manual sending/receiving, all of them are again flagged as junk. Doesn't matter if you run junk mail controls after the unmarking or not. If she is going through the inbox, unmarking the junk "flame" one by one, if there are 5 or 6 emails on a page (no preview), before she is able to unmark the last one on the page, all previously unmarked emails are all the sudden being marked as junk again! Just doesn't make any sense....

I saw this myself today on an outlook.com account. I don't know if that is relevant, but when messages move from folder to folder, we can't rule out some server side shenanigans. You've mentioned gmail, but I take it that is the sender's account, not the troubled user?

Mine were spam messages so I wanted them labelled as Junk, but every time I did so, they popped up again in the Inbox. A notable feature of these was that the sender's supposed display name was itself an email address wrapped up in quotation marks. This takes me back to my previous question; are there any "funny characters" in the affected addresses? I was thinking about '+' which can be used to create temporary addresses in Gmail, but in my case I'm wondering about the quotation marks.

To clarify a couple of things:

- The receiving email account (the one using Thunderbird) is a Yahoo (actually AT&T) account, on Windows 8.1 - the receiving email account is set up as IMAP in Thunderbird

- sending email account (which is the one that gets flagged as junk) is a GMail account (send from a Mac, I assume via the web UI of whatever browser that user is using)

- the emails that are being flagged as junk are the the all the in inbox, nothing is moved into any other folders, so there are no "server side shenanigans moving from folder to folder" - those emails are not in any (obvious) way flagged as spam when checking the account via the Yahoo web UI

My Thunderbird is set to move messages to Junk when I manually mark then as Junk. Moving them to Junk can involve the server, if the junk folder is set to be on the server. And you've said the account uses IMAP, so there is a possibility that the server is part of the problem.

Is yours set to move on marking as Junk? If not, does changing it affect this problem? Does setting the account to use the Junk folder in Local Folders make any difference?

And are there any "funny" characters in the affected email address?

Yahoo classifying them as Spam (or not) is or should be irrelevant. The orange flame is specific to Thunderbird and has no significance to the email server.

Is there anything like spamassassin or local anti-spam software in use which might be adding headers giving a spam score to these messages?

If you set a filter to move messages from this sender to another folder immediately on receipt, might this defeat the irrational Junk labelling?

Zenos said

My Thunderbird is set to move messages to Junk when I manually mark then as Junk. Moving them to Junk can involve the server, if the junk folder is set to be on the server. And you've said the account uses IMAP, so there is a possibility that the server is part of the problem. Is yours set to move on marking as Junk? If not, does changing it affect this problem? Does setting the account to use the Junk folder in Local Folders make any difference? And are there any "funny" characters in the affected email address? Yahoo classifying them as Spam (or not) is or should be irrelevant. The orange flame is specific to Thunderbird and has no significance to the email server. Is there anything like spamassassin or local anti-spam software in use which might be adding headers giving a spam score to these messages? If you set a filter to move messages from this sender to another folder immediately on receipt, might this defeat the irrational Junk labelling?

As mentioned, the emails in question are in the inbox, no folders involved.

And no, there is no other anti-spam software involved (that would be an obvious issue, considering that I am working myself for 39 years in IT)

And no, I have not tried to set a filter for her, as that would be to confusing for her. And there aren't any "funny characters" in those emails, this is for a lot of them just the simplest one, two sentence communication back and forth between the sender and recipient, absolutely nothing fancy...

According to the docs, spam filtering should not apply in the first case, as the sender's email address is in the address book, those been whitelisted and not being processed for spam to begin with...

Ralf

I asked about "funny characters" in the email addresses, not in the messages. I'm looking for reasons why Thunderbird might not recognise legitimate Contacts whose addresses are in the Address Book.

I am not a mind reader. I don't and can't know what additional software might be in use, nor the life story of a poster.

I suppose it's a slip of the finger, but we are talking here, I think, about Junk, not Spam.

By and large, Thunderbird does whitelist against the Address Book successfully. This function doesn't appear to be fundamentally broken. The puzzle is why specific addresses are mishandled. I know that + is problematic, and it seems from my experience that deliberately malformed email addresses using quotation marks to embed a fake address into the display part might fool it too. Neither of these particular considerations might appear to apply in your case, but I do recall a long and heated discussion about Thunderbird's allegedly totally useless filters and only after many postings did it emerge that there was a + symbol in the affected address. I have been unable to find any authoritative list of such characters and why they might be treated differently by Thunderbird. The solution there, which was filter related, was to change the filter mode to "contains" rather than "is" but it taught us that Thunderbird is blind to certain characters and so cannot match addresses that contain them.

Our Address Book is prone to corruption too, so a rebuild of the Address Book might be productive. Or just removing and re-adding the affected Contact.

Is the user's Junk filtering of any benefit to her? Is it successfully disposing of a lot of genuine junk? If not, it may be expedient to disable her Junk Controls.

Thanks for the replies and suggestions. Here is a bit more info from my observations and investigations:

Zenos said

Are there any "funny" characters in the affected email addresses?

I looked at the handful of email addresses that show this incorrect Junk status. None of them have "funny" characters. In fact, all of them use only letters, not even numbers.

PCWorxLA said

- the emails that are being flagged as junk are the the all the in inbox, nothing is moved into any other folders, so there are no "server side shenanigans moving from folder to folder"

Same with me. My incorrectly labeled emails are not in folders nor have been moved and are still in my inbox.

Stranger still, for some of these senders, only some of their emails are incorrectly labeled as junk. All the incorrectly labeled emails have been sent since May 2015. But not all emails after May 2015 for some senders are incorrectly labeled. I am perplexed...

Per Zenos' suggestions, I attempted to rebuild my address book by deleting my global-messages-db.sqlite file and then restarting. I also deleted one of the entries from my address book, exited and restarted TB, re-entered the address, exited and restarted. But the incorrect junk labeling persists.

At this point, this is an annoyance more than an issue for me. But I wanted to reply with more data in case an idea/solution jumps out to someone.

The address book is stored in files with the .mab extension. As far as I know, the sqlite files you have deleted do not affect the Address Book.

I have options to associate certain address book with certain accounts. These include settings for which address books are to be used as whitelists. Could you check your Junk settings (under Account Settings) and make sure you don't have any similar options, specifically any that might prevent a specific address book being used to whitelist.

The options I'm thinking of may have been added by an add-on, but occasionally such features sneak into the core application. Similarly, I'd look at Tools|Options (I can't remember if it is under security or privacy) but there is a list of addresses and domains where these can be set to blocked or allowed and so can override the general concept of the address book being used as a whitelist. Having said that, this list is about permitting or blocking remote content and ought not impinge on Junk classification.