try clicking the repair button in properties to force a reindex of the actual mail file. What is reveals might be a good result or it might nit.

Thank you for your reply, I did that but to no avail.

try the view menu and setting the folders to ALL.

thanks again, that setting is on ALL

I am not a specialist but could rebuilding the database be a solution ?https://www.uslsoftware.com/global-database-in-thunderbird/#:~:text=to%20rebuild%20it%3F-,Global%20Database%20In%20Thunderbird,inside%20the%20Thunderbird%20profile%20folders.

The file size is large 1,8 Gb the number of message indicated if I view the properties of the folder is much larger than the number that appear in the inbox so I assume that for some reason that the database query does not return all the information

would rebuilding Folders help? Try Rebuilding Folders in Mozilla Thunderbird Before implementing the steps, make sure that Thunderbird is closed and is not running in the background.

Open the location similar to: C:\Users\<Username>\AppData\Roaming\Thunderbird\Profiles\xxxxxxx.default-release\ Go to the data folder i.e., ImapMail or Mail folder as per your account configuration. If the problem is with your Inbox, carefully delete the Inbox.msf file. (DO NOT tamper with files with no extension, only delete MSF files) Now, start Thunderbird. It will rebuild the MSF file and show all the messages.

Deleting the msf files is the same as Repair Folder, but the proper rebuild process is to delete the msf and the mbox files, both of which will be automatically recreated when TB restarts. This sometimes fixes the discrepancy between the folder size reported in TB and the size shown in the profile folder.

http://kb.mozillazine.org/Compacting_folders#Real_fix

thanks very much I can see the inbox file but not the inbox.sbd file...... could that be recreated ? since it seems to be a subdirectory?

I followed the instructions precisely made a folder and copied all mail in that folder, then deleted inbox and msd file etc. restarted I now have an empty inbox.... I restored the original inbox file but I still have an empty inbox (I have a copy of the all mails from the inbox in a seperate folder that indicates total 12600 unread 2155. Is there a way to count the visible emails in the inbox quickly? then I can compare the number of visible emails to the number of 12600 indicated at the bottom of the inbox screen secondly I am rather confused why the restore of the inbox file 1,8 gb does not return the inbox to its previous state.

If the account is IMAP, the rebuild will re-download the messages from the mail server, but if it's POP, as it appears to be, the rebuilt Inbox will be empty until new messages are downloaded, but it should now work like a normal folder. If the original Inbox appears empty, you may not be able to recover it unless you have a readable backup.

If the account is POP and it's set to leave messages on the server after download, you can force the server messages to download again by renaming the popstate.dat file in the account subfolder of Mail in the profile folder, while TB is closed.