Is your question that you want to change default to unthreaded? If so, here is the info: This is the official (to my knowledge) documentation. Well worth the read https://support.mozilla.org/en-US/kb/message-threading-thunderbird

Here is my own documentation on threading, duplicating the above, but it may help: You need to highlight each folder and click View>sort by>unthreaded. If this applies to just a few folders, just repeat the process as necessary. If you have many folders or plan to add many new folders, you may wish a different approach, below:

More info: To change default for *new* folders, In config editor, you can change default that applies to NEW folders you set up: mailnews.default_view_flags 0=unthreaded

Config editor is available at Tools>settings>general and scroll to bottom right.

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To set many *existing* folders, follow these steps: (I creates a crude video that walks through the steps at

   https://davidkirk.org/SettingDefaultFolderView.mp4  that demonstrates the following steps:

   First, highlight a folder that you have set to unthreaded	
   In the Message List view, in the column header, on the far right, open the options button that shows    
    context menu. :
   At the very bottom is the option:
   -> "Apply current view to..."
   -> "Folder and its children..."
   -> Hover over an account
   -> In the next menu don't select a folder. Instead select the account name itself.

Thank you for the response. I already know to how sort by date and then group by sort as is my preference. My question is how to set the default view to all collapsed.

I have multiple email accounts. When I switch from one inbox to another, the view is expanded. I can collapse them with "\". But, when I switch back to the inbox, it's all expanded again. I want the default view to be collapsed rather than expanded. Is it possible to do that? I really don't like all expanded.

I am confused. I thought that is what I explained how to do. Maybe I'm misunderstanding what you mean by 'collapsed.' I inferred you meant unthreaded . My apologies

No worries. It was on me for not being as clear and detailed as I needed to be. Again, thank you for answering!

I've been searching this for a while. It doesn't seem to be possible even with config editor. Also in searching, I've seen most questions in the past have been people asking how to expand by default. I guess Thunderbird is giving the majority of users what they want. That leaves the minority of users like me who prefer a collapsed default view without options other than manually collapsing every time when going from one email inbox to another to view messages (I have multiple email accounts that I like to keep separate rather than in a unified inbox).

I can't find a way to set a default for this, but I did find that a single press of the backslash ("\") key will collapse all the threads in the current view.

To add to my earlier reply ("a single press of the backslash ("\") key will collapse all the threads in the current view"), I've also discovered that once collapsed, the next time I navigate to that folder, all the threads remain collapsed.

In other words, it appears that it's only necessary to collapse the threads in any specific folder one time. ...cheers!

Using the "\" key does collapse the threads, but for me, that isn't retained after switching to another account and back. It also misses the point that we want our threads to be restored the way we left them, not automatically expanded or fully collapsed. Personally, I like to keep every date grouping collapsed except "Today", which I like to be expanded. So when I switch between accounts, I want to see today's emails only.

Hitting the \ key worked for me. It immediately collpased all threads

They stayed that way...surviving switching to different folders and back again countless times and also closing down and then reopening Thunderbird

All good....Thank you !

I am running version 115.6.1 and have been trying since updating to version 115 to get the folders in all my accounts to stay collapsed when I open Thunderbird as it used to do in version 102.

However, when Thunderbird opens, the folders that had received messages in the previous session are always opened in expanded layout and the others are collapsed.

If I want all the folders to open in a collapsed layout, then I have to collapse all the folders in every account and exit Thunderbird. I then have to open Thunderbird without receiving any new messages and exit Thunderbird with all the folders in every account in a collapsed layout and only then will Thunderbird open with all the folders in every account in a collapsed layout.

Can anyone suggest how to change Thunderbird so that it always opens with all my folders in a collapsed layout without me having to open and close Thunderbird twice, every time, which is not helpful at all, as this did not happen in the previous 102 version of Thunderbird!!!

Thanks.