Please show us a screen shot with the contents of Local Folders in the Mail folder of the Thunderbird profile.

Here it is. BTW I am running the current TB on the current MacOS. Mail was transferred from Postbox.

Thanks for the screen shot. In your Local Folders I see two files, Inbox2009 and Inbox2010, which could contain messages from those two years. All your *.mozmsgs folders have been created by the Spotlight search and of no interest in your case.

Postbox uses the mbox format to store messages, so normally Thunderbird should recognise this format. If I understand you right, the folders Inbox2009 and Inbox2010 in your folder pane > Local Folders are empty, although they weigh respectivement 213 MB and 153 MB? If you try to open one of those files with Text-Edit.app can you see some message text beginning with the following lines?

From - Mon Mar 24 14:17:42 2025 X-Mozilla-Status: 0001 X-Mozilla-Status2: 00000000 X-Mozilla-Keys: X-Account-Key: account1 X-UIDL: 20f65f2a00a0d46722ec0c007678198f Return-Path: <msprvs1=201686_SbRx5Y=bounces-1-3@bounce.nytimes.com>

Maybe this discussion https://support.mozilla.org/ml/questions/1456225 could be helpful for you?

Here is this beginning of Inbox2010:

From - Sat Jan 02 15:40:09 2010 X-Account-Key: account2 X-UIDL: 8255-1214424788 X-Mozilla-Status: 0001 X-Mozilla-Status2: 00000000 X-Mozilla-Keys: Return-path: <noreply@caremark.com> Received: from host38.caremark.com ([unknown] [63.72.182.38])

by vms172049.mailsrvcs.net
(Sun Java(tm) System Messaging Server 7u2-7.02 32bit (built Apr 16 2009))
with ESMTP id <0KVM00DXNYS4FC3V@vms172049.mailsrvcs.net> for
wcassano@verizon.net; Sat, 02 Jan 2010 14:12:04 -0600 (CST)

Received: from dalptl1 ([198.187.114.171]) by caremark.com ([172.16.2.5])

with ESMTP (TREND IMSS SMTP Service 7.0) id 958082070002cfa0 ; Sat,
02 Jan 2010 15:18:45 -0700

Date: Sat, 02 Jan 2010 14:11:01 -0600 (CST) From: noreply@caremark.com Subject: Caremark Portal Registration Confirmation X-Originating-IP: [63.72.182.38] To: wcassano@verizon.net Message-id: <104692310.1262463061345.JavaMail.wasprtl@dalptl1> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit X-TM-IMSS-Message-ID: <958082070002cfa0@caremark.com> Original-recipient: rfc822;wcassano@verizon.net

Welcome to Caremark.com!

"Maybe this discussion https://support.mozilla.org/ml/questions/1456225 could be helpful for you?"

I followed those instructions exactly when first migrating from Postbox to Thunderbird. It didn't work. Also tried to correct the problem with the Add-on ImportExportTools NG which also didn't work. I didn't always get a progress bar when using these tools, but when I did, it never indicated that the job finished, even after waiting for an hour.

Yesterday for testing purpose I installed Postbox and created a profile with one account. Profile path, folders and files are almost the same as in Thunderbird. (see image). Then I imported the Postbox profile in Thunderbird 137, without any problem (second image with Local Folders imported from Postbox)

In your screenshot of Local Folders in the Mail folder the mbox files do not have their normal symbol and their "kind" is labelled as Unix Executable. By chance I also had a problem with one of my folders in Local Folders: my folder "Total_Energies" surprisingly had been renamed by TB in "Total_Energies136d755c" and was displayed as empty in Thunderbird although the corresponding mbox file is indicated with 9.2 MB in the profile. Even after deleting the "136d755c" suffix TB didn't display any message in this folder.

Then I remembered a recent discussion in the German Thunderbird Mail DE forum https://www.thunderbird-mail.de/forum/thread/96253-tb-128-6-1esr-64-bit-mails-in-lokalen-ordnern-verschwunden/?pageNo=1 about a solution to "repair" such a damaged mbox file. I opened the file with BBEdit.app, saved the file as "Total_Energies.xml" as shown in my third image, moved it in my Local Folders in Mail and restarted TB. Now all messages of this folder are again visible.

I think this is worth a test: download BBEdit from the Mac App Store and install it in Applications folder. To begin with open your Inbox2009 folder in BBEdit.app and save it (as shown in my image: look for "Line breaks" and "Encoding" !!) as file Inbox2009.xml (you can later delete the .xml extension) Move this file in your Local Folders in Mail and start TB....