You keep talking about a folder called 'Junk' but mention you are using IMAP with a hotmail address which is using server Outlook.com

I would have expected you to be talking about a folder called 'Junk Email '

re :Account Settings> Server Settings>When I Delete a Message>Move it to> "Deleted"

Does the server actually use a folder called 'Deleted' or is it called 'Deleted Items' ?

re: DELETED Folder - If any Unread Messages, they disappear immediately when the Folder is opened. DELETED contains the messages I manually deleted from JUNK but none that ThunderBird deleted from INBOX, JUNK or DELETED

re :Junk Settings> Destination and Retention>Move new junk messages to JUNK> Checked

Accoring to this link: https://support.microsoft.com/en-us/office/working-with-message-folders-in-outlook-com-6bb0723a-f39f-4a8d-bb3f-fab5dcc2510a

This really sounds like you are not using the default server folders.

Please logon to the outlook.com webmail account and post an image which shows all the folders on the server, just so we both can see the same set.

But if I'm right - you need to get the accounts using the correct folders first.

eg: Junk Settings > Destination and Retention Select 'Move new junk messages to' Select 'Other' and choose 'Junk Email' on hotmail account

For deleted emails Server Settings When I delete a message: select 'Move it to this folder ' choose 'Deleted Items on hotmail account'

You may not have the 'Sent' set up correctly - info suggests the server uses the 'Sent Items' folder. In 'Copies & Folders' Select 'Place a copy in' Select 'Other' and choose 'Sent Items on hotmail account'

Thanks for your review.

Junk Folder You are correct that the Folder on the Outlook Server are "Junk Email" and "Deleted Items", but are identified as "Junk" and "Deleted" in ThunderBird. The "Sent" and "Sent Items" Folders have the same out of sync problem.

See Attached for a Folder layout on Outlook.com and on ThunderBird

I tried to change the Junk and Deleted Folders to agree with Outlook, but the folders were not available to choose. I then tried to Subscribe to the Folders but they were still unavailable after a Refresh. Is there another way to get the Folder Names to align?

Thanks again for your assistance.

The server 'Junk Email' folder does contain the correct four sub folder as identical to 'Junk' in Thunderbird. So it has synchronised ok in that respect. It is also showing one unread mail in Junk same as Junk Email and also the 'Rule to be....eted' folder has 2 unread which is identical to server.

There are occasions when servers display folder names which when synched up to mail accounts seem to offer a different name. It's a pain as it makes it not so easy to check out what is going on. But it is the one and the same folder.

I would advise you check all the folder mapping for the default folders and use the 'Other' option. eg: Junk Settings > Destination and Retention Select 'Move new junk messages to' Select 'Other' and choose 'Junk on hotmail account'

Whilst in Junk Settings : Is this setting selected ?

• 'Automatically delete junk older then X days'

uncheck to not auto empty.

re :The DELETED ITEMS Folder on the Outlook server contains 11,274 messages, which includes the ones I think are being automatically deleted.)

In Thunderbird please check this setting: Account Settings > Server Settings right side under 'Message Storage' 'Empty Deleted folder on Exit' - is this selected ? If yes, It would explain if emails are getting removed everytime you exit Thunderbird in which case do not select that checkbox.

Also check the 'Deleted' folder right click on 'Deleted' folder and select 'Properties' Select 'Retention Policy' tab It should say to use the account settings.

Why are the emails in 'Deleted Items' still visible on server ? Because in Thunderbird you have not compacted the 'Deleted' folder or compacted all the folders. And Outlook has not emptied any of the displayed emails.

re :When Junk Opened, Most of the messages disappear When you select that 'Junk' folder it synchronises with server and the first thing it does is get updated to show what is on server. So, if emails disappear and seem to disappear from Deleted as well - it is because those emails have already been deleted off the server, so Thunderbird cannot display what does not exist.

Note: Outlook.com is auto emptying the Junk Emails and Deleted Items folder on a regular basis. They mention 30 days, but I'm not sure if there are settings in webmail to do this at eg: 5 day interval. I believe there is a 'sweep' clean option in webmail which can auto delete certain junk from a specific sender - so check the webmail account to see if has been set up.

https://support.mozilla.org/en-US/questions/1387793?utm_campaign=questions-reply&utm_source=notification&utm_medium=email#answer-1530794

Note - if the server spam filters had put email into Junk Email, it may have been in the 'Junk Email' folder for longer than you think especially if you do not click on 'Junk' every day. In Thunderbird Check this setting:

• Right click on 'Junk' folder and select 'Properties'
• Is this checkbox selected 'When getting new messages for this account, always check this folder'

If no, then if Outlook server spam filters had put email in that folder, you will necessarilly not know about it until you actually clicked on 'Junk' to synchronise folder.

Apparently - if you delete a message that is in the 'Junk' folder, then it should get moved to 'Deleted', but if Outlook empty the 'Junk Email' folder then it goes directly to a 'hidden' purges folder, which Outlook then clean up within a set period which maybe hours.

If the Outlook webmail account has a load of junk emails in 'Deleted Items' folder then it might help to explain whether the deletion is coming from Thunderbird or not.

You mention a Message Filter - : 1 SPAMAssassinYes (Before Junk Classification)

But that filter should not be required because you have set up the following which does the same 'after junk classification'

In Account Settngs > Junk Settings: 'Trust junk mail headers set by SpamAssassin' > Checked that setting means if SpamAssassin flag is set then send it to Junk.

You mention 12 Message Filters which are running after Junk Classification. 12 to Delete the Message (After Junk Classification)

But what are the parameters - For example have you set them up with this: if Junk Status is Junk then Delete

In which case the emails which were set to go to junk are now going to Deleted.

Or are these emails the sort that would never get flagged as junk because they are not spam but you just don't want them.

Thank you for the effort expended and the insight on how ThunderBird and Outlook coordinate.

Responses to your 3 posts:

1 Spam Assasin The Message Filter - : 1 SPAMAssassinYes (Before Junk Classification) appeared automatically after I checked Account Settngs > Junk Settings: 'Trust junk mail headers set by SpamAssassin' > Checked . Originally. I thought I had to buy a copy of SpamAssassin for this to function. As a test I unchecked and the Message Filter remained. I then deleted the SpamAssassin Message Filter and then checked Account Settings > Junk Settings: 'Trust junk mail headers set by SpamAssassin' > Checked and the SpamAssassin Message Filter did not reappear. I left the SpamAssassin box checked. UPDATE, when I shut down and restarted ThunderBird, the SpamAssassin Message Filter reappeared.

The 12 Message Filters are all set to DELETE MESSAGE. As a test, a week ago, I changed them to SET JUNK STATUS=Junk and MOVE MESSAGE TO DELETED Folder. The Message Filter Log ballooned to 10,000 lines in a few hours: some Messages appeared in the Log as many as 104 times. I changed back quickly. Most of these Messages are Contest Winners, Lawsuit, Mortgage,. There are a couple of URLs that send messages on every topic imaginable. The Adaptive Junk Filter Log indicates that either ThunderBird or SpamAssassin are identifying some of the same Senders that my Message Filters are identifying, albeit using different criteria

2 Outlook Neither Outlook or ThunderBird are set to empty the Trash Upon Exit. I noticed that Outlook has apparently changed the default Junk days from 30 to 10; but my problem appears immediately even before I exit ThunderBird. My default action is to leave ThunderBird in the background as long as my laptop is on.

The large number of Messages in the Outlook Deleted Items Folder do no appear when the Folder is accessed, but when the RECOVER ITEMS DELETED FROM THIS FOLDER. Today 18 appeared immediately; this is the same Count as in ThunderBird, a quantity of 6,816 available to Recover.

3 Folder Sync I changed the Destination and Retention Options to OTHER. The Automatic Delete box has always been UNCHECKED.

Account Settings > Server Settings right side under 'Message Storage' 'Empty Deleted folder on Exit' = NOT CHECKED , although the verbiage is TRASH instead of DELETED FOLDER. Account Settings > Server Settings right side under 'Message Storage' 'Clean Up (Expunge) Inbox on Exit' = NOT CHECKED.

The DELETED Folder > Properties > Retention Policy is to use my account settings>Don't delete any messages

When I open the Junk Folder, if there are only a few Messages, the Unread count immediately goes to blank and the messages do not appear in the message pane, If there are many messages (or my old PC is stressed) I can seethe Unread Count decrease and Unread message appear in the message pane and I can see them either unbold or strikethrough (or sometimes both) before they disappear. The Unread Count in the Deleted Folder increases (until I access that Folder.)

A few days ago, I attempted to compact all Folders and chose the option to automatically compact (after notification) any time 20 MB could be saved. The Dialog box appeared shortly, but has not reappeared. I did not notice any behavior changes.

The Sweep option has not been activated on Outlook.

'Junk' folder > 'Properties' > 'When getting new messages for this account, always check this folder' > is CHECKED.

(This box is NOT CHECKED for the Deleted Folder.)

I made the changes you suggested; hopefully they will solve the issue,

re : The 12 Message Filters are all set to DELETE MESSAGE.

The Message Filters are best used to sort and move good email. Otherwise you can end up with zillions of Message Filters just to cope with the ever increasing and changing adaptations of spammers. It can become crazy, but is usually not required if you train the Junk Controls. The adaptive Junk controls - set up in 'Junk Settings' are best used for spam/junk. but you have to train it by selecting 'Not Junk' or 'Junk' on emails you receive. Aftre a couple of weeks it starts to learn what you want to go to the Junk folder.

re :When I open the Junk Folder, if there are only a few Messages, the Unread count immediately goes to blank and the messages do not appear in the message pane, If there are many messages (or my old PC is stressed) I can seethe Unread Count decrease and Unread message appear in the message pane and I can see them either unbold or strikethrough (or sometimes both) before they disappear. Just for gathering a visual reference: Next time you start up Thunderbird - do not select the 'Junk' Folder. Leave it alone and let it receive whatever emails get sorted into that folder.

Logon to the Outlook webmail account and see what is displayed on server. Select the server 'Junk Email' to see what it contains. Create an image as a means of reference.

Take an image which shows the Thunderbird 'Junk' and webmail 'Junk Email' folders side by side. So we can see the unread and total count of both.

In Thunderbird, now select the 'Junk' folder to see contents. Do not select any emails. Create another image showing 'Junk' in Folder Pane and its list of emails in Thread Pane. Check the outlook server view - is the same - you might need to refresh.

re :and I can see them either unbold or strikethrough (or sometimes both) before they disappear.

The 'strikethrough' is created because the email has been set to be deleted but not manually by clicking on 'Delete' because the 'mark it as deleted' option is not selected.

It is possible, that those emails may have set as 'Junk' by Thunderbird because spamassassin had set a flag and your settings say 'trust spamassassin' OR in the past you physically trained the junk controls by marking email as junk or not junk but it has a 'strikethrough' which means you have also set a 'delete' on the same email.

You have 12 Message filters set to Delete the Message (After Junk Classification) Those messages may have already been picked out as junk regardless. I think it is your 'Message Filters' which say delete that are deleting the messages which would have gone to Junk anyway. So basically, email gets Junk flag so is put in Junk and then it's deleted due to filter, so it is not really in Junk, hence when you select the 'Junk folder, it updates with server and the messages you set as deleted - are erased from the updated view.

The Message Filters are probably responsible for what you think are disappearing emails. You would be better off not using Message Filters for junk and instead train the Junk controls to recognise what you deem as junk.

I have Un-Enabled all my Message Filters (except for the ThunderBird-created SpamAssassin one) and shut down/restarted ThunderBird. I will advise the results later.

Your latest email went to Junk despite me Marking the previous three as NOT Junk.

In the 'Junk Settings' Did you select your address books as a whiltelist, so Thunderbird knows those as good email addresses?

Then you could add the 'Mozilla Support Forum email address located in 'FROM' to an address book.

Please see attachment showing the results of turning off my Message Filters. The 6 messages in the Junk Folder were not Marked As Junk, but they behaved as expected, ie, turned to READ when manually Marked As Junk, did not disappear, moved to the Deleted Folder when deleted and remained visible in the Deleted Folder. They were no messages identified in the Message Filter Log and 1 message was identified by Adaptive Junk Filtering which was in the Junk Folder and is now visible in the Deleted Folder.

The 6 were probably in Junk as a result of my Outlook directive to allow only SafeSenders into my Inbox. Should I change this option to allow Adaptive Junk Filtering to function as intended? I will monitor for a few days to allow a more representative number of messages to be processed.

For my other HotMail account, I did not disable the Message Filters. For this account, 4 Unread messages were in Junk and they behaved as expected. My Message Filters identified and deleted 13 messages and Adaptive Junk Filtering identified 1 message which was in the Junk Folder and is now visible in the Deleted Folder. None of the 13 messages identified by my Message Filters were in the Junk or Deleted Folders. I will change some Message Filter Actions from DELETE to MOVE_TO_DELETED as a test.

Yes, I have Address Books in the WhiteList and will add no-reply@mozilla.org.

I appreciate your efforts to resolve this issue.

Thanks for your assistance and explanations of how ThunderBird functions. Based of my new understanding I offer the following explanation.

My problem is a result of my misunderstanding of how ThunderBird processes DELETED messages. A manually Deleted Message is Marked AS Deleted and moved to the Deleted Folder, however, if a Message Filter action is to DELETE the Message, the message is moved to the Deleted Folder and automatically and permanently deleted.

I changed my Message Filter Actions to 1) Set Junk Status, 2) Move to Deleted, 3) Stop Rule Execution. Messages are processed as follows: 1) Appear in the Junk Folder temporarily before moving to the Deleted Folder either after waiting a bit or opening the Junk Folder (or any other Folder), 2) Junk Status is set to Junk, 3)Read/UnRead status is UnRead. All as expected.

I consider this situation SOLVED. (User misunderstanding again.)

Again, thanks for your understanding and explanations which led to this solution.