re: removed a file called oldmail (with all its subfolders) files do not have subfolders - so your explanation is rather confusing.

Please post an image of the directory showing the original 'file(s)' before you did anything to it.

A senario: If you had a folder called Oldmail in your Thunderbird Folder Pane with no emails, and it showed subfolders lets call them OldInbox and OldSent which do contain emails. Looking like this in Folder pane: -Oldmail ~>>OldInbox -->>OldSent

In your Profile folder name > Mail > account name folder you would see: Oldmail - an mbox file with no extension not containing emails Oldmail.msf - an indexing file OldMail.sbd - a Folder

In the OldMail.sbd folder you would see: OldInbox - an mbox file with no extension containing emails OldInbox.msf - the indexing file OldSent = an mbox file with no extension containing emails OldSent.msf - indexing file

assume the OldMail mbox file had no emails, so all emails were in OldInbox and OldSent.

So if you only backed up the OldMail.sbd folder containing those mbox files with emails.

Then when you wanted to put them back, you would have created a new 'OldMail' folder in 'Local Folders' keeping the exact same spelling, so you could see it in the Folder Pane. then closed Thunderbird and accessed the profile folders. In Mail folder you selected to open Local Folders Account then copy pasted the OldMail.sbd folder into Local Folders, so OldMail.sbd folder was in the same place as OldMail mbox file and OldMail.msf,

you would not be needing to rename anything, so I'm wondering what you have done.

Well, I see I made a silly mistake. In 2003 I grouped several sub folders under one which I called mail2003. This became a folder (with a bunch of old subfolders) inside the local folders. Then I started to create new folders inside the local folders (not inside mail2003, which was not used any longer). I still work with many folders and subfolders. At a certain point, I copied the whole folder mail2003 into the default profile as a backup for future possible use, to save space, and forgot it. Now I have to search the file mail2003 for a certain issue. So I copied mail2003 back from the default to the local folder (with all its old sub folders -each subfolder with its file and its snm and msf). Renamed mail2003 as mail2003.sbd, but of course I don't have the index. So Thunderbird does not see it. I really don't need it there, that is the way I tried to review all those old emails up to 2003 in search for a specific info.

The simple option is use the import export tools add-on https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/

This add-on adds an entry to the tools menu. With the knowledge that Thunderbird's native storage is MBOX. Use the menu system to import that which you backed up.

It is easier on you and us as we do not have to go into the intricacies of the actual file names etc.

Thanks, Matt. I've installed the tool and nothing happened. I've noticed that the import function has a limit of 100 characters. Those emails had years of collected material; maybe that was the reason. I've also noticed that my Thunderbird is starting to behave in a strange mode. For instance, all but one of the messages which I had in one subfolder called "politics" simply disappeared. I am mentioning an existing subfolder, it has nothing to do with the old mail2003 that I've been trying to install. I even think it disappeared before I've installed the add-on. I could bet that it is a bug in the new Thunderbird version 31.7; but I've noticed it only after installing the add-on.

Go to the tools menu (alt+T)... There is a new entry on the bottom called import export. use those menu entries to import your old MBOX files. You actually have to drive. This is not an automatic Microsoft fixit file.

I am willing to be it is not a bug. Your anti virus might be hyperactive though.

Ok, Matt. Problem solved. Thanks a lot.