More information is needed, as IMAP accounts repopulate on new profiles. Once you log into the account, the messages should appear.

Hi. Thanks for your help.

After import of profile (thunderbird import or ImportExportNG) : - all pop and imap accounts are present. - all accounts contain all messages (with body, attachments...). (IMAP accounts have offline downloaded messages saved into profile files, with no internet connection, you can read offline emails).

So, the restore of profile is perfect and full. Nothing is missing.

I quit thunderbird. I launch thunderbird. (with the right profile which contains the restored datas : thunderbird -ProfileManager ).

No account is missing (pop or imap) but some accounts have zero folder and zero message (on display, perhaps still into file).

Other accounts have all their emails and folders.

So I don't understand what is the problem.

My understanding is that messages are missing from IMAP accounts. What happens when you attempt to retrieve new messages? Any error messages?

No message is missing into profile accounts backuped.

Here are screenshots to confirm.

To be sure, computer is switched to offline internet connection, so no data retrived from imap servers, only local files are used.

I delete existing profile, create a new profile (thunderbird -ProfileManager)

A ignore first account creation at thunderbird startup.

Then, "Menu/tools/import/import from another thunderbird installation", then "choose profile folder".

I launch import, processing...

Result is on column 1 of screenshot (left column) : You can see a list of several emails accounts. Some have total emails sum, other no sum (but contains emails and folders).

I choose one of account which will loose datas displayed : the yahoo account. You can see column 2 all folders restored, trash contains 1300+ emails, ...

All accounts are restored, emails and folders, I can read offline stored emails without internet connection enabled, all is perfect (except some account with sum count regenerated);

So, now, I quit thunderbird (menu/quit), nothing else.

I launch thunderbird.

You can see Column 3, yahoo acount deployed : now only one folder "inbox" ("courrier entrant" in french language), no message (message list empty on the right : black background) into inbox folder, all disapear.

Same results if I use ImportExportNG instead of Thunderbird import function.

I suppose instead import function I can't try to use direct remplace/copy of profiles folders into data folders, because the backup is an older thunderbird version (no error during the successfull import displayed).

Your screenshots were not included. My inference is that your IMAP accounts are not signed in. IMAP accounts always sync to the server, not to the PC. So, if you have messages on PC and access an IMAP account that does not access the actual account, IMAP logic is to make the local folder match the online folder. Since the online folder is empty, the local messages are deleted. I suggest you use your online access to the account to verify that there are messages there. Then, when you actually log in with the IMAP account, messages will appear.

The screeshot was updated during you replyed to me. Sorry. You can see it now.

Outside this question, when I used thunderbird Offline mode, it didn't destroyed my local downloaded copy of server emails and I can use thunderbird offline to read my emails.

So I am not sure this may be the reason.

And I tryed to setup, after a successfull import, thunderbird to permanent offline mode before restart it, to disabled server attempts.

True, if you stay offline you can read messages, but if you go online, thunderbird will attempt to retrieve messages. If it fails, the messages in account folders will be deleted. If the account no longer exists, I suggest that you copy the messages to Local Folders and then delete the account.

I understand your answer.

Thanks for your help.

Subsidiary question: If the only goal is to restore an old backup and consult the contents, without continuing to make active use of Thunderbird (connecting to a server, writing email), would the possibility of setup the files (which ones?) in "read-only" mode have been a solution to prevent the local cache from being erased? Thanks.

You're making life complicated. if all you want to do is view mbox files, you can use your search engine to look for 'free mbox viewer' and not use thunderbird at all. There is also a free online viewer, requiring no software: https://www.mbox-viewer.com/