In Thunderbird

• Help > Troubleshooting Information.
• click on 'Open Folder' button

a new window opens showing contentents of profile name folder.

• Close thunderbird now.

• Click on 'Mail' folder
• click on the Pop mail account which is displaying those popstate folders.

the 'popstate.dat' file keeps a record of what has already been downloaded, so that TB does not download them again.

You should only have one 'popstate.dat' file per pop mail account. It should be in the mail account name and not in any other folder such as one with a.sbd which contains subfolders as mbox files. see image below. popstate.dat files should not display in Folder pane.

Do you have popstate files that do not have the 'Type' as 'DAT File'? maybe they are Type 'File', so appearing as if an mbox file? they should not have any popstate.msf file either. If unsure you could post an image for checking before deleting.

You can delete popstate files, but try to leave the original correct one alone.

If you delete all of them, including the correct one by accident, the worst that can occur is that TB will download again anything left in the server Inbox.

mbox files contain emails and have no extension. They have a 'Type' described as 'File'. They have same name as the folders in the Folder Pane. There will also be a*.msf indexing file for each mbox file.

Start Thunderbird.

If you cannot see those files and folders, you may need to make hidden files and folders visible. http://kb.mozillazine.org/Show_hidden_files_and_folders

Hi, I enlisted the aid of my son and your instructions seem to have fixed the problem. At the time he worked on my computer there were 30 folders! Thunderbird looks much more normal now. Thank you. Bob