Where is the new email appearing if not in the inbox? Do new messages show in the numerical notification? Is the repair function working? What OS are you using? Is it IMAP or POP3?

The new mail does not appear at all until i use the "repair folder" option. It then appears in the inbox. Yes it appears in the numerical notification. The numerical notification does not function properly as it no longer shows the number of "new" e-mails. The repair function allows me to see the new mail but I have to use it every time I get new mail. Windows 11, 24H2 POP3 Thanks for the response.

I have also reinstalled Firefox.

We could delete the Inbox and get TB to regenerate a new Inbox.

I always take some precautions so, although you may think some of these points are irrelevant, please don't miss any out.

This will work with the Inbox Folder because it's a system folder. But there are always implications with doing this procedure with other folders so don't try this with others.

1. Write down the name of the Account in which the Inbox is located that needs regenerating. Empty the Inbox of all emails. Everything inside will be deleted.

2. Close Thunderbird. Close all other open programs (I always do this to make sure nothing interacts with the program I'm working on).

3. Make a Folder on your Desktop. Call it what you will.

4. Open: C:\Users\[Users]\AppData\Roaming\Thunderbird\Profiles\XXXX.default-release

5. As we are going to be deleting a Thunderbird System Folder in a POP account, access the 'Mail Folder'.

6. There are folders in here that relate to each of your POP3 accounts and also to your Local Folders. Open the folder that relates to the account under which you are having the problem with the Inbox.

7. There are two folders named 'Inbox'. One is just 'Inbox' the other is 'Inbox.msf'. MOVE - do not delete - both these files into the Folder that you made on your Desktop.

8. Keep this system folder open that you have just removed the Inbox files from.

9. Launch Thunderbird.

10. The POP3 account that we've just deleted the Inbox from will no longer have an Inbox (probably). Click on the root of this POP3 account and a new Inbox will be created. I've done this so that, if there was an irreparable corruption, we're starting from something that is clean.

11. Check the folder you have kept open and two new Inbox files will have been made. Close the folder.

12. Run this for a while and see if it has made a difference. Also keep the files for a couple of days that you removed in case there are implications that might need you reinstalling them.

I would be grateful if you would post a response here to tell me if this has resolved your problem. This is for my info so I know I can use it again for other people with the same problem.

Can I just send all in my inbox to my gmail account (there aren't that many). and then delete TB completely including the profile?

You can do what ever you want to - but that doesn't repair the folder or diagnose the problem. If you have the time to do as you want and you're happy with what you're doing and the implications, who am I to stop you? My suggested action would take less than 2 minutes.