If this is an imap account - are those emails visible to read on the server - accessed via webmail account ? If yes: It is possible the emails are indeed intact in the Inbox mbox file. But the index file is incorrect and not pointing to a correct email. You could try repairing the Index file:

• Right click on Inbox folder and select 'Properties'
• Click on 'Repair Folder'
• click on 'OK'

If you have an Anti-Virus program which can scan any file you open or try to fix any email it finds odd, then you can find the mbox file gets corrupted because AV programs do not understand that an mbox file is not just one emails it may be hundreds of them. In these cases the index file is not touched and so still uses original data. So appears out of synch. I would advise you do not let the AV mess about with Profile folders and definitely never set an auto fix or any kind of fix on anything in Thunderbird.

Thank so much for taking the time to come back to me.

I tried the repair but now I have lost all of the emails that had previously been blank. Is there anything I can do now to get these back?

Thanks again

Pauric, Can you share what version of Thunderbird you're on and 32-bit or 64-bit? About->Help Can you also share the size of your inbox? Right click -> properties

Hi Corey,

Thanks so much for trying to help!

The "About Thunderbird" tab tells me that the version is 128.1.1esr (32-bit). It says it's up to date.

Maybe there was a problem during the updating process? I have a few other email accounts on the Thunderbird and there isn't any problem with those ones.

Thanks again.

Thanks Pauric, do you by any chance know when your Thunderbird install was updated to the 128.1.1esr version? In other words, do you think this happened on 128.1.1esr or could it have happened on a 128.1.0esr?

Hi Corey,

I couldn't be certain but there may, indeed, have been an update around the time the emails disappeared (maybe about 10 days ago). Is there a way to roll back to the earlier version? Would that solve it?

Thanks again for your help!

I'd expect going back a version isn't going to recover your messages.

Please right+click on the folder > properties. What size is shown?

Also, what antivirus software do you use?

Hi Wayne,

Thanks for the message. The file size is shown as 314 MB (for 299 messages), which is a lot less that it should have been.

I am using Norton Antivirus (for quite a long time now). None of the folders for my other email addresses are affected.

Thanks again Wayne.

re :I tried the repair but now I have lost all of the emails that had previously been blank.

That means those emails were aleady gone and only the index file had a register of them. I would strongly advise you do not let Norton have access to your Profile folders OR at the very least never allow Norton to auto fix or manual fix any file in your thunderbird profile. See image below as guide - I use Norton as well, but would not want it to try and fix anything as the risk if of loss of emails is not acceptable.

Are you talking about an imap mail account or a pop account ? If you logon to your webmail account via a browser do you see all those missing emails? Have you compacted that Inbox manually or automatically? Suggest DO NOT compact anything.

Possible options to try for recovery: Maybe the mbox file has a load of 'marked as deleted' emails which can be recovered providing you have not compacted the Inbox. Make a note of the oldest email you can see - it's date and subject eetc.

Option 1. In Thunderbird

• Help > Troubleshooting Information
• Under 'Application Basics' - half way - Profile Folder - Click on 'Open Folder'

A new window opens showing contents of profile name folder.

• Exit Thunderbird now - thi is important.

• If you use Pop accounts - click on 'Mail' folder
• If you use imap accounts - click on 'ImapMail' folder

• Click on the pop or imap account name folder to see contents.

The emails are stored in an mbox text file called 'Inbox'. It has no extensions. The index file will be called 'Inbox.msf'

• Open that 'Inbox' mbox file using a text editor program such as 'Notepad++'

Emails are written to the file one after the other, so oldest will be at the top and newest at the bottom. So you can easily see if there any old and currently not visible emails. Each email will start with these lines: this is an example

1. From - Sun Dec 28 18:14:40 2014
2. X-Mozilla-Status: 0015
3. X-Mozilla-Status2: 00800000

• Use 'Edit' > 'Find'
• Search for this line: X-Mozilla-Status: (not X-Mozilla-Status2:)

If you see numbers like this 0009 or 0019 then they have been marked as deleted and are currently hidden. Basically if you edit that number so it says 0001 then it can be recovered. If in doubt then you could edit all the emails to say 0001

See images below as a guide.

• Make sure the X-Mozilla-Status: has the number 0001
• Save the file.
• delete the 'Inbox.msf' file. A new one will be auto created.
• Restart Thunderbird.

If this recovers any emails in Inbox where you altered that X-Mozilla-Status to 0001.

Option 2: Logon to your webmail account via a browser. If you see all the missing mails in Inbox of webmail account and use a pop account then you could force a complete download of whatever is still in server Inbox by deleting the pop acount 'popstate.dat' file. The popstate.dat file keeps a record of everything previously downloaded, so that when it connects to server Inbox, it only downloads emails it has not downloaded before.

Yes it will mean anything already downloaded will get downloaded again. In Thunderbird

• Help > Troubleshooting Information
• Under 'Application Basics' - half way - Profile Folder - Click on 'Open Folder'

A new window opens showing contents of profile name folder.

• Exit Thunderbird now - thi is important.

• click on 'Mail' folder
• Click on the pop account name folder to see contents.
• locate and delete this file : popstate.dat

• Start Thunderbird

The popstate.dat file is now a clean new and empty file, so everything currently on the server in the Inbox will get downloaded again.

Option 3: Use a backup. Do you have a backup? Assuming you keep emails in default location and use Windows OS...Did you backup this 'Thunderbird' folder ?

• C://Users/User name/Appdata/Roaming/Thunderbird

Thanks so much for all this information and apologies that it's taken me so long to come back to you.

On Option 3, I don't think I have any backup (or at least I never took any specific steps to back up the folder). Not the smartest maybe!

On Option 2, it is a POP account but webmail is only showing the same list of emails that is in the Thunderbird platform

On Option 1, a few odd things. Firstly, in the Mail folder, there are 3 files. Two of these were created on the same date in 2019 and the third one in August this year, the date that the earlier emails disappeared.

Secondly, when I opened the earliest Inbox mBox file, (which was enormous), only a handful of emails appeared with various X-Mozilla-Status codes, including at least one which had the 0001 code but still didn't appear in the Inbox.

If you had any further ideas, I'd really appreciate it!

re :On Option 1, a few odd things. Firstly, in the Mail folder, there are 3 files. Two of these were created on the same date in 2019 and the third one in August this year, the date that the earlier emails disappeared.

Sounds like thunderbird could not detect the original pop mail account and created another and that is the account you are currently viewing. As it was a new account folder, it would have a new 'popstate.dat' file. It would have downloaded everything that was on the server at that point. So the current pop account now looks the same as the server.

re :On Option 1, a few odd things. Firstly, in the Mail folder, there are 3 files.

I'm presuming you mean folders and one of them was called 'Local Folders' - created in 2019. The other was the original pop account created in 2019. The current pop account probably has the same name but has a number appended.

re :Secondly, when I opened the earliest Inbox mBox file, (which was enormous), only a handful of emails appeared with various X-Mozilla-Status codes,

Please confirm you are talking about the original pop account created in 2019. That sounds odd - every email in that file should have a line X-Mozilla-Status: the numbers may vary, but 0001 will reset as a normal read mail. What size was that 'Inbox' no extension file ? You said it was enormous, so that implies it contains a lot of emails.

Q: What anti-virus product do you use?

You could attempt to point the account to the older mail account just to see if emails reappear.

In Account Settings > Server Settings Bottom right is 'Local directory:C.....etc. You said the Mail folder contained 3 folders and new account dated august 2024, but another of same name one was a date in 2019 Currently that 'Local directory' will point to the new mail account dated august - probably same name as original but they added -1 number to the account. Either manually delete the -1 number OR Click on 'Browse' and reset to look at the one dated 2019 which probably has same name but no added number. Then exit Thunderbird, wait a few moments for background processes to complete and start Thunderbird. Check that mail account. If you see any emails - right click Copy to and select a folder in Local Folders.

The idea is to rescue any mail and then reset the 'Local directory' back to new one dated August 2024.