I forgot: The instruction I followed was displayed here: https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

The image you posted shows a folder hierachy, but it is wrong. I'm not surprised it has not worked.

In MAC OS, Profile folders are located here:

~/Library/Thunderbird/Profiles/<Profile name>/ The tilde character (~) refers to the current user's Home folder, so ~/Library is the /Macintosh HD/Users/<username>/Library folder.

and it is the 'Profile name' folder that would contain the 'Mail' and 'ImapMail' folders. The 'profile name' folder typically has this type of structure : 123vbg45.default

So if you had followed instructions to copy the Libary > 'Thunderbird' folder then it would have copied the whole lot.

The 'Thunderbird' folder itself contains the 'Profiles' folder and the very important profile.ini' file which tells Thunderbird what 'profile name' folder to use, plus a few additional required files. The 'Profiles' folder would only contain the 'profile name' folders. The 'Profile name' folder would contain a whole bunch of files that allow Thunderbird to get access to all the mail accounts and that includes the 'prefs.js' file and all the address books etc etc.

It really looks like you created a Thunderbird folder on external hardrive and then backed up/copied just the 'Mail' and the 'ImapMail' folders and put them into the external drive 'Thunderbird' folder. If that is the case, then you do have the stored emails for the pop accounts, so all is not lost. It is possible to extract the mbox files and .sbd folders.

But until your folder structure is better understood and possibly corrected it just not worth messing about.

What your image does not show is whether you actually have the following structure. Did you copy/paste the backed up Thunderbird folder into the Library/'Thunderbird' folder , so it looks like this?

• /Macintosh HD/Users/<username>/Library /Thunderbird/Thunderbird

and that highlighted one is the one you copied in.

Q: Do you have a 'Thunderbird' folder in a 'Thunderbird' folder ?

Please select the 'Thunderbird' folder which is in the 'Libary' folder as highlighted below

• /Macintosh HD/Users/<username>/Library /Thunderbird/Thunderbird

So you see the contents of that 'Thunderbird' folder - the hierarchy will display on left - so make sure it includes the 'Libary' in the display so that I know what is going on. When that Thunderbird folder is selected, all the files and folders that would be displayed on the right hand side. I'm expecting it to contain a 'Profiles' folder and some files. Post an image showing this.

Thank you, Toad-Hall, for your answer. I have added two pictures:

20210410-Thunderbird-local-library.jpg shows the directory "/Macintosh HD/Library/Thunderbird" that will be opened by Thunderbird on "Help" > "Informationen zur Fehlerbehebung" (information to work on errors?) > "Profilordner" (profile directory) > button "Show in Finder". This is the directory I know and the directory from which I have backed up my mails before setting up the computer. Hereto I have copied my backed-up mails.

20210410-user-without-library.jpg shows my directory "/Macintosh HD/Users/<username>". I don't see any "Library" here. I expect it to be be hidden. Unfortunately my old commands I have used in 2017 (!) to display hidden files in the Finder do not work anymore. I have to find out, display the files again, and make another screenshot. I will do so later in the evening.

Thank you again, Nachtkrabb

Hoooray! I found the directory "/Macintosh HD/Users/<username>/Library/Thunderbird"! And it contains a directory "Profiles", see the newest picture (20210410-Thunderbird-USER-library.jpg). As I haven't known about this directory, of course I didn't save it...

Please, what can I do now to restore my mails?

And do I understand correctly: My Thunderbird-mail-addressbook is lost, isn't it? Is there a possibility to restore at least a part automatically from the mails, as soon as they are restored?

Thanks from N.  :-)

Hoooray! I found the directory "/Macintosh HD/Users/<username>/Library/Thunderbird"! And it contains a directory "Profiles", see the newest picture (20210410-Thunderbird-USER-library.jpg). As I haven't known about this directory, of course I didn't save it...

Please, what can I do now to restore my mails?

And do I understand correctly: My Thunderbird-mail-addressbook is lost, isn't it? Is there a possibility to restore at least a part automatically from the mails, as soon as they are restored?

Thanks from N.  :-)

copying the entire contents of /Macintosh HD/Users/<username>/Library/Thunderbird to ~/Library/ on big sur should do it.

Toad-Hall wrote: "~/Library is the /Macintosh HD/Users/<username>/Library folder"

So I should copy the entire contents of /Macintosh HD/Users/<username>/Library/Thunderbird to ~/Library/ = /Macintosh HD/Users/<username>/Library?

Thus "/Macintosh HD/Users/<username>/Library/Thunderbird/Crash Reports" becomes "/Macintosh HD/Users/<username>/Library/Crash Reports" etc.?

And where come the mails from my backup into the game...?

I am sorry, Matt, but I am not sure if I understood your proposal. Thank you Nachtkrabb

...or should I copy everything from "/Macintosh HD/Library/Thunderbird" to "/Macintosh HD/Users/<username>/Library/Thunderbird"...?

N.

...which is what I just did. Well, I have one mail address with not so important mails where I cannot destroy anything. So I added this as POP3-mailing. I do not see any old mails after restarting Thunderbird.

Thunderbird 78.9.1 is installed on the flight.

....?

N.

You have now found where your current Thunderbird is actually located. There are two 'profile name' folders called '2u24clgq.default' and 'bsfhy4m4.default-release', but what do they contain and which one are you currently using? This is the first info we need to know. If this was a completely new installation, I was expecting to only find one profile, so let's check out what is going on first. I'm now wondering if you actually still have all the old stuff still there.

In Thunderbird Help > Troubleshooting Information Under 'Application Basics' near the bottom of the list is 'Profiles' - click on 'about:profiles' A new tab opens It will list those two 'profile name' folders. Please post an image that shows all the content. This will tell us which profile is currently set as the default one.

You will see the '2u24clgq.default' profile mentioned.

• Root Directory': /Macintosh HD/Users/<username>/Library/Thunderbird/Profiles/2u24clgq.default

at the end of the line it will say 'Open Folder' - click on it. It will open in another window. Make sure the view actually shows all the files and folders and also the 'modified date' and 'Size' columns. Post an image showing all the contents of that '2u24clgq.default' folder - you may need to post more than one image.

Then access the other profile name folder:

• Root Directory': /Macintosh HD/Users/<username>/Library/Thunderbird/Profiles/bsfhy4m4.default-release

at the end of the line it will say 'Open Folder' - click on it. It will open in another window. Make sure the view actually shows all the files and folders and also the 'modified date' and 'Size' columns. Post an image showing all the contents of that 'bsfhy4m4.default-release' folder - you may need to post more than one image.

Hi Toad-Hall, thank you for your precise questions.

The first image "20210412-Profile-Overview.jpg" shows the overview inside Thunderbird. The second "20210412-2u24clgq_default-bsfhy4m4_default-release-1.jpg" shows the content of 2u24clgq.default plus the upper half of bsfhy4m4.default-release in overview. The third image "20210412-bsfhy4m4_default-release-2.jpg" shows the lower part of bsfhy4m4.default-release in overview.

Then I navigated into bsfhy4m4.default-release, opened all the subdirectories and took four further screenshots. I will post these with the next. The upload keeps doing strange things.

As written above, I copied my backup stuff into directory "/Macintosh HD/Users/<username>/Library/Thunderbird".

"Änderungsdatum" is "date of change", "Erstellungsdatum is "Date of creation".

I'm getting curiouser and curiouser. N.

...Then I navigated into bsfhy4m4.default-release, opened all the subdirectories and took four further screenshots. Here they are.

...Now I navigated into my backup, see the following pictures. This is not complete, but I could do it if necessary. I am a little bit shocked as some mail directories are EMPTY that should'nt be.

Before this machine went to Apple for repairing and setting up afresh, it wasn't working dependently. And then it crashed and wouldn't start up any more... I get what I can...

N.

Looking at the last set of images showing backup. In 'Mail' folder, there is another folder called 'Local Folders' and also folders called 'pop3.web-1.de' and 'pop3.web-2.de' and pop3.web-3.de'.

Let's start with 'pop3.web-1.de' - second image above. At the moment those images only display a tree hierarchy of 'Mail' folder showing folders in general. I can see there are various folders, but most are .mozmsgs folders and some are .sbd folders. But that is what I expect to see in 'Folder' hierarchy type of view.

I need you to actually open the 'pop3.web-1.de' folder so it displays all the contents of only that folder - all the files and all the folders. Then post images showing all the contents of the 'pop3.web-1.de' folder.

The 'pop3.web-1.de' folder also contains some folders with a .sbd extension eg: _Arbeit_2018.sbd Open the _Arbeit_2018.sbd folder to see all the contents - post image. Same for any other .sbd folder in the 'pop3.web-1.de' account name folder.

Repeat the above for 'Local Folders' and 'pop3.web-2.de' and pop3.web-3.de' folders. Then we will know what those folders contain.

Regarding all the folders that have a .mozmsgs extension: Each .mozeml file is a partial copy (up to 20kb) of a message in the mail folder, stored in a .mozmsgs subdirectory folder. It is used by the optional Spotlight Integration component under OSX. It's deleted when the message in the mbox is deleted. These are not the stored emails that Thunderbird uses.

Do not open any of the .mozmsgs folders. They do not contain any mbox files.

I am sorry I couldn't write before: I am ill since my operation and my father is in hospital. One could say I am a little tiny bit preoccupied.

Gosh... What DID happen on saving that stuff...?! pop3.web-2 is simply empty.

Here come the pop3.web-1-pictures. The directory name is always displayed in the footer of the window.

To make it easier, I add the pop3.web-pictures in the following message.

I needn't have bothered. Here come the pop3.web-picture with the pop3.web-3-picture (in the singular each). I have moved the pop3.web-3-picture hereto from above.

Again the directory name is always displayed in the footer of the window.

After your description that the .mozmsgs folders are not important and we need mbox files, I do get cold feet. Is there anything to be done...?

Thank you for your help and patience says Nachtkrabb

In the background Artie Shaw plays his famous "Nightmare". Anything to add?

The view you are showing is a folder view hierachy and so I would only expect to see folders not files.

AS an example, below is an image showing a folder hierachy, but if I open a folder then I will see what it contains. Folder hierarchy on left, but select folder to see contents and it is shown on the right. Perhaps it is your computer that shows things the way you have posted. I am using a Windows OS.

If you select the mail account name folder eg: 'pop3.web-1.de', it should show you what it contains. The images you posted when you selected that folder, does not seem to show everything in the images. Do you need to scroll down to show the lower section. The mbox files in 'pop3.web-1.de' will be after all the *sbd folders, but the image you show for backup 'pop3.web-1.de' only show all the *.sbd folders. When you selected a .sbd folder, it does not show any useful files. This is looking not so good.

Hallo Toad-Hall,

thank you very much for your answer. As I haven't recovered after an operation yet, I can't react as fast as I would like -- please pardon me.

Well, I have an Apple Macbook, so the pictures look a little bit different from yours. But I have shown you all the details as you described earlier. There are no mbox files anywhere...!!! I expect that there is nothing to be done, then?

Have a good time Nachtkrabb