Make sure you have Set up junk controls correctly.

• Right click on imap mail account in Folder Pane and select:' Settings'
• select 'Junk settings'
• select 'Enable adaptive junk mail controls for account'
• Select all the address books you want to use as 'Whitelist'
• Select: Move new junk to
• Select : 'Other' and choose the server imap Spam folder.
• Click on 'OK

• Menu icon > Options > Security > 'Junk' tab
• Select: 'When I mark messages as junk'
• Select: 'Move them to the account's Junk folder'
• Select: 'Enable adaptive junk filter logging'
• click on 'Reset Training data' button.

• click on 'OK

Make sure the email address(s) for Yahoo Group emails is in one of those address books you selected as 'whitelisted' in junk controls.

Junk Controls now needs training as you have cleared the old data. Telling Thunderbird what is 'Not junk' is just as important as telling it an email is 'Junk'.

• Select the 'Spam' folder.
• select the email so it is displayed.
• click on the 'not junk' button.

• Repeat same action for each of those emails.

Suggest you create a folder for those yahoo group emails.

Suggest you create a filter:

• Menu icon > 'Message filters'
• make sure 'Filters for' is the correct account
• click on 'New'
• Give filter a suitable name
• select 'Manually Run'
• select 'Getting new mail'
• select :'Filter before junk classification'
• select 'Match all of the following'
• 'From' and 'contains' and type email address

If you have more than one email address:

• Change: select 'Match any of the following'
• After entering the 'From' etc line, click on the + icon to be able to another identical line with different email address.

Perform this action

• 'Move Message to' and choose folder
• click on 'OK

New incoming mail should get moved before junk classification runs.

• Make sure the filter is enabled.

• click on 'Filter Log' button
• Select: 'Enable the Filter Log'
• OR if already enabled, click on 'Clear Log' button

This now starts a fresh report. Then you can monitor filter actions.

• click on 'Close'

You could (but do not have to) run this new filter on the Inbox, where you have just moved the spam emails into when selecting 'not Junk'.

• Select the filter name
• Run selected filters on and choose the imap Inbox
• click on 'Run Now'

Thanks Toad, As a test - I would like to revert back to a earlier version of TB to see if that resolves my problem - but it doesn't appear that is possible.

As my original post implies, I am not a novice to Thunderbird and have been using their Junk Email settings for many years and have created many filters to keep non-junk email from getting into the junk folder. I also turned Spam Assassin off both at my email server and in TB a long time ago because it also picks up non-spam.

Yesterday I shut down TB, renamed the entire TB directory in AppData-Roaming-Thunderbird, and downloaded/installed a new TB. I made sure Junk processing was OFF, Spam Assassin was OFF, and there were NO FILTERS. WIth this configuration I do not see any way that TB should move my email around - yet it still does.

SO - Currently I should have NO filers, junk processing, or Spam Assassin involved with TB email. And checking my filter-log, which is typically very busy, none of the problem emails were logged - and since turning all filters off several days ago NOTHING is being logged (as expected).

I get a LOT of email from sources that are not in my address book since I work on several websites and get a lot of email from folks I have never met. Fortunately a lot of that email is generated by forms I have on my various websites and I can identify them with Message Filters to keep them out of Junk mail.

THIS IS A NEW PROBLEM. It started about 5-6 weeks ago, and I remember updating TB at about that time. Yesterday I looked and found a later update available and installed release 60.7 but that did not help.

The problem primarily happens for a couple of specific emails, but unfortunately I get a lot of those specific emails, and one of those is one that is often time sensitive.

The time sensitive email is from a web form I created years ago. The form actually calls an email generation routine that has not changed for about a year. The same email routine is used for several forms, but only one of them seems to be landing in SPAM folder. Investigating the email headers I can see no difference in the headers for the emails that work vs the ones that go to SPAM,

One big thing does stand out. Until this happened I had NEVER seen any email in the SPAM folder, and I don't even remember there being a SPAM folder. I suspect it was created by my hosting company's IMAP email process but can't prove it.

I am convinced this is a TB problem because I have found is that I can TURN TB OFF, and use the web interface for my IMAP account. I can then move the back to my inbox and it stays put - UNTIL I START TB UP AGAIN.

Also, TB is the only thing that has changed on my end. I am told that my hosting company has not made any changes either, but I have found in the past that level-1 support often doesn't have a clue to what changes have been made.

Thanks, Hank

I reverted back to a 6 month old vdersion today and the problem did not go away. I guess that rules out the idea of the latest update being the problem.

It looks like my only choice is to delete all my filters and retrain junk collection. All of that has been turned off already so I don't expect any resolution but who knows ........

Toad, I tried rolling back to an earlier version and I still had the same problem - BUT later found that TB is doing auto update! I have attempted to turn that off but it still updated every time.

SO - I tried your settings, resetting training data, and marking messages as not-junk (repeatedly). As I mark them as not-junk they move back to the inbox, but soon move right back to the spam folder. New messages of the same source and type still go to the spam folder. And if I manually move them to the inbox they soon are moved back to the spam folder. And there is no record of anything moving in either the security/junk log or filters log.

I did create a filter and while that does AVOID the problem, it does not FIX the problem. And using the filter would just require me to check for new email there every few minutes - not an option!

With spam and junk options turned off NOTING should automatically move out of the inbox.

Thanks for trying, Hank

re :SPAM folder. I suspect it was created by my hosting company's IMAP email process but can't prove it.

Thunderbird will only create a 'Junk' folder and it is used for Pop mail accounts. Thunderbird does not use the word 'SPAM'. It is a server folder created by hosting company and used in the webmail account for Spam/Junk emails. Imap accounts are usually auto subscribed to see default server folders, such as Inbox, Sent, Spam, Drafts, Trash.

But marking as not junk should have fixed issue.

Try this: In Thunderbird Help > Troubleshooting Information click on 'Open folder' button A new window opens showing the contents of your 'profile name' folder.

Exit Thunderbird now.

Click on 'ImapMail' folder click on the imap mail account name folder

Delete the 'Spam' no extension folder - it will only exist if you dowload full emails. Delete the 'Spam.msf' folder

Start Thunderbird.

Thanks Toad, Digging into my profile found a lot of old stuff around and reminded me of past problems. It's been several years since I last poked around and a lot has changed. I really need to clear some of my old renamed/saved files out! I did take the opportunity to tune some of my server settings.

ANYWAY - SURPRISE - I decided to use the webmail interface on the host. I shut down TB and logged into webmail - RoundCube. I did this several weeks ago as a test and everything worked perfectly for over an hour - which is what told me the problem had to be in TB.

LAST NIGHT - While TB was shut down completely, the problem showed up on the server!

So I am now once again trying to convince the hosting company it is their problem.

Thunderbird does not recognize the IMAP SPAM flag. this is not a biggy for most people, unless you use Yahoo who constantly put mail with the spam flag back in the bulk mail folder.

While I doubt that the server side issue is caused by that, unless the web service also does not recognize the flag and has the same result as Thunderbird.

The bug in Thunderbird has been fixed in versions after 67, so the 68 beta that is currently out will offer the fix, but might have issues with some of your older add-ons and going back to the current version after testing can be an issue as the profile needs to be manually restated.

The bug also contains discussion about the "correct" and semi standard flags. It might shed some light or at least suggest questions you can ask of your provider. https://bugzilla.mozilla.org/show_bug.cgi?id=1260059

My hosting provider insisted that they were not moving my email but suspected some client was moving the emails.

I changed the password on the mailbox and sure enough things stayed put! I fired up TB with the new password and everything was fine.

Problem wound up being NOT TB, and it was NOT the ISP! Unknown to me, the Android-Mail app on my Samsung S8 "smart" phone was TO SMART. It was marking email from 2 sources as SPAM. Finding documentation was nearly impossible, and following the options on Android O/S was almost as difficult.

If the user "marks" an email as SPAM it adds it to a filter list and future emails are moved to the SPAM folder by the Android App.

So apparently I had somehow managed to mark 2 emails as SPAM (I didn't know there even was such an option, and still don't know where it is.)

After finding the problem I searched Google for reports. Eventually I found ONE report from several years ago.

All seems to be working now.

Thanks for all the help. At least this forced me to clean up some of the mess of old email and folders.