Hello. I'm disappointed that there has not been any response to my plea for help 2 months ago. The situation has not changed. After a new message has arrived, thus changing the colour of its folder name to blue and adding an asterisk, sometimes, seemingly randomly, the colour changes back from blue to black and the asterisk disappears. I can no longer risk messages arriving automatically, and so have unticked 'Check for new messages every _ minutes' and 'Automatically download new messages'. I have got into a routine in the past 2 months. When I click Get Messages, I sit with a pen and paper and scribble down the names of the folders shown as having new messages. Then I can, leisurely, open them and see the new messages or guess which ones are new if the message asterisk has disappeared. An example of this illustrates my frustration. Today, clicking Get Messages downloaded 24 new messages in 18 folders; I left them alone. Within about 5 minutes, the blue colour of 13 of those folders had reverted to black, with no asterisk. If I hadn't noted which folders had new messages, I would have had no way of knowing they contained new messages. After looking at all these folders, I found 22 of the 24 messages; I have no idea where the other 2 are, and can only hope that they were not important. This situation is not what I would expect from 'the leading open source, cross-platform email ... client'. This was not an issue until a few months ago. Thunderbird had been fine, and highly recommendable, in all the years (about 14) that I've used it, until recently. Now, unfortunately, it is not reliable. Can anyone tell me: 1. the condition that needs to be satisfied for a change in the colour of a folder name from blue to black; 2. the signal that triggers removing the asterisk from an unread message, while still leaving the message subject in bold? I would be really grateful for any such information so that I could then experiment with changing settings. Cheers.

1. the condition that needs to be satisfied for a change in the colour of a folder name from blue to black;

You select the folder to view contents. You do not select folder, so it remains blue, but then you exit Thunderbird and later on start Thunderbird. Folder now displays black to show unread mail.

So the 'Blue' is new means new for that session until you select to open it.

2. the signal that triggers removing the asterisk from an unread message, while still leaving the message subject in bold?

click on Folder called 'A' with new mail in Folder Pane - see email set as new showing asterisk - but do not select to read. Leave as it is. Then select another folder, when you return to the folder with that new unread mail, the email will remain as unread in bold but the asterisk is now gone. So the asterisk only remains whilst folder is newly open drawing attention to new unread mail since last time that folder was opened. The asterisk will disappear if email is selected. If email is not selected, the 'new' mail asterisk is applied until you go away from folder after which it is no longer new mail since folder was last opened.

'New' mail is only new since last time that folder was opened.

re : Within about 5 minutes, the blue colour of 13 of those folders had reverted to black, with no asterisk.

Version 78 does not apply an asterisk to the folder. The new icons are outlined and no longer folder icons.

You mention filtering emails to various folders. You could use those same filters to help improve locating new mail. You could create a 'Tag' called eg: NewToDo and give it a Blue colour. In the filter under actions add an action to 'Tag Message' and choose the 'NewToDo' tag. Once you have dealt with an email with 'NewToDo' tag you remove the tag. Then you will have a record of everything you received that's new, but not read and sorted. So even if you lost that new blue colour on folder or lost the asterisk on new email, the emails would still have the Tag you applied, so easy to locate.

The following is an option you should consider to improve work flow. Use search and create a search folder.

• 'Menu app icon' > 'Find' > 'Search Messages'
• Choose the account name rather than a specific folder
• select to search subfolders
• Match all of the following
• 'Status' 'is' 'New'
• click on 'Search'
• Select 'Save as Search folder'
• Choose where to save and give folder a name eg: New

Then that folder will appear in the account. It will contain emails with the 'New' status, but you need to select that 'New' folder and work through those emails before going to other folders otherwise you may inadvertantly trigger removal of 'new' status.

So, I would add an amendment. Use the filter to set TAG as described previously and then set the 'New' search folder actions to these:

• 'Match any of the following'
• 'Status' 'is' 'New'
• 'Tags' 'contains' 'NewToDo'

This saves you from searching through a load of folders and even if you inadvertantly select a folder that triggers removal of 'new', you will still have new emails with the Tag and all visible in one search results folder. Just remember to remove the tag when you have dealt with the email.

At any time you can update that 'Search' folder called 'New'. Maybe you added or removed a folder, so want to be certain the search results are correct. right click on 'New' search result folder and select 'Properties'. You can select what folders to search and even add folders from another account at this point. you can also edit the search parameters if required.

Another alternative to see only folders with 'unread' mail: 'View' > 'Folders' > 'Unread' This alters the folders shown in Folder Pane to only those folders with unread messages.

Many thanks for your responses. However, as I explained, the change from blue to black can happen to some of the folders even when I do not select any of them. The problem does not involve exiting Thunderbird; I appreciate that if I exit and re-start Thunderbird, all folders will be black. To reiterate, after downloading new messages, folder names change to blue and, typically, if I do not do anything at all and just sit there, some of the folders revert to black within a few minutes. If the two conditions shown in '1.' are the only ways to make the colour change, something must be making Thunderbird think I have selected a folder and then left it. Do you have any ideas? Could it be to do with filtering, or somehow refreshing? Similarly, from '2.', the lack of a message asterisk implies that I had previously selected the particular folder and then left it, even though I hadn't. For your second response, my apologies - I must have been thinking of the older version. However, the principle is the same, with just colour change rather than colour change and asterisk change. As I submit my reply, I've just come across your third response. Many thanks for that as well. It will take me some time to work through the details. Once again, many thanks for your help. Cheers.

The idea of using the 'Tag' and the Search folder is not a fix for the weirdness of your folders turning black when they should be blue, but it is a viable method of you not losing track of all those 'new' emails so to improve your work flow whilst you have this issue.

If a folder has 'new messages and not opened, but then recieves more 'new' messages they should still all be marked as new.

The default directory location for thunderbird to store messages is :

• C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\Profiles\<Profile name>\

What is the directory location you are using?

As a test, next time you open and run Thunderbird, could you open Thunderbird in 'Safe Mode' and use in that mode for a good length of time to test whether the folder turn blue with new and stays blue until selected. https://support.mozilla.org/en-US/kb/safe-mode-thunderbird

Thanks very much for all this. I'll investigate the Tag and Search procedure in due course. Since I'm using Thunderbird Portable Edition on the PortableApps platform, the Local Directory for storing messages is: G:\PortableApps\ThunderbirdPortable\Data\profile\Mail\<account name> I have used Thunderbird with Add-ons Disabled (Safe Mode) for several days, and, unfortunately, it's still the same - blue folders sometimes revert to black without being touched. I've also tried it in another computer but with the same result. Is it any help that all this seemed to start around the beginning of November 2020? I'd be really grateful for any other thoughts. Cheers.