Local folders is a "special" account in Thunderbird. It is local storage and has nothing to do with your choice of IMAP or POP to retrieve your mail.

Check in your profile folder as you apparently are there if you have more than one foldertree.json file. My guess is you do.

Hi Matt, I appreciate your answer. I checked the profile folder and there is only one folderTree.json file. There are several other json files, like folderCache.json, directoryTree.json, session.json etc. But only one folderTree.json. When I open that notepad file in my browser, I see what appears to be a list of all my folders, including my imap folders. It includes the folders that are invisible. Here is an example of a file name of a test folder I created that doesn't show in the TB app "mailbox://nobody@Local%20Folders/u%20test%20last". It is folder #558 in the list. Here is an example of a file name that does show in my TB app "mailbox://nobody@Local%20Folders/MISC/Electronic%20Devices/Lenovo" (It is a sub-folder in my MISC/Electronic Devices folder). (#31 in the list) As a test, I just added a new sub-folder into that MISC folder, and I see it in the app and the profile. But anything I've added after a sub-folder called "mailbox://nobody@Local%20Folders/trading%20ACCOUNTS/TS%20Pers%20FUT-OPT%20-CLOSED" (folder #71 in the list) doesn't appear in the app when I close and reopen it, although the file number appears to be the order the folders were created as file #549 is visible. There are a lot of sub-folders since I had to re-create some of them when they didn't appear in my app the next day. Any other ideas where to look? Thanks for your help.

close Thunderbird and delete the foldertree.json file. A restart of Thunderbird will recreate it. See if that helps at all.

Thanks. I did that but get the same result. I'm wondering if changing the file names directly in the json file and in the mail/local folders folder so that they now are listed in one of the visible sub-folders would be a workaround. Or would that just stop that file working? I'll give that a try tomorrow and see how far I get with a single unimportant sub-folder unless I hear otherwise before I get to it tomorrow. I'm doing a backup as I write this. By the way, I'm an Aussie living in LA. Thanks again.

mailbox://nobody@Local%20Folders/ indicates the folder exist in Thunderbird in the local folders account. Therefore your mail server has nothing to do with the folders being visible.

Have you tried using the all folders folder view in Thunderbird. Post Supernova (115) I have observed the other folder types to be a bit unreliable.

Hi Matt In View/Folders, All Folders is checked. I checked all the other options as well and all that did was add more sections with duplicates of what I had. But no previously invisible folders showed up.

What I ended up doing was to go to my Local Folders/Email folder which lists all files, visible and invisible, so I duplicated the .msf file and the data file of a visible folder, then changed the name of the two new files. Then I opened TB and, surprise, there they were :) I quit TB and reopened, and they are still there, so I'm hoping this is a work around, and when I have enough time, I will be able to retrieve all the invisible folders this same way. It doesn't answer what made the folders invisible in the first place, but I haven't lost anything except a lot of time and some hair.

I'm interested to hear what you think about this, but otherwise I should be good to go.

Thanks for your assistance.