The mozmsgs folders are for Windows Search. Instead, copy the mbox files from

C:\Users\username\AppData\Roaming\Thunderbird\Profiles\8characters.default\Mail\Local Folders

to the same location on the new computer. The mbox files have no file extension and appear with an .msf file of the same name. Ignore the .msf files, they will be created automatically on the new computer when you start TB.

Just when I thought I had it figured out: copy the .mozmsgs folders; ignore the .msf folders. Now it turns out I should ignore both and only move the files with no extension! Anyway, thanks for your very prompt response. I will try this immediately. But what about subfolders where the parent folder has a .sbd extension? Should they be moved, too?

Oh, and another question, if I may: All these archived message folders will end up under Local Folders in my new computer. But is there any way to replace the "built-in" Sent messages folder (currently empty on the new computer, of coursre) with the very large existing Sent messages folder on my old computer? Thanks!

The .sbd folder indicates it's a subdirectory. It may contain mbox files. Importing folders with a complex subfolder structure may be easier with ImportExportTools NG.

If the account is POP, you can move the existing sent messages to the new Sent, although it won't provide any advantage. If it's IMAP, you could move small numbers of messages at a time, as this involves uploading to the IMAP server. But if you don't need access to the old sent messages on other computers, just leave them in Local Folders.

Again, many thanks for your help.

1. I think I'm going to stick with the manual copy-and-paste method rather than Import/Export. So my choice for recreating my current structure is either to (a) move over the .sbd folders along with the folders that don't have an extension, or (b) move over the subfolders individually and then try to move them under/into the current parent folders on the new computer. Will option "a" even work or am I left with "b" by default?

2. It is a POP account, and I'd like to have the stored Sent messages on my old computer show up in the primary Sent folder on my new computer. (If I create a separate Sent folder under Local Folders, they won't be integrated with the messages I send going forward.) So my question is where, exactly, do I paste the archived Sent folder in the TB tree so that it replaces/overwrites the existing (empty) Sent folder?

1. (b) is simpler, but try (a) in a limited way and see if it works.

2. Select the messages (Ctrl+A to select all) in the Local Folders Sent and move them to the primary Sent with drag and drop. Copying the archived Sent mbox into the empty Sent folder should achieve the same thing.

1. I went with option b, which worked fine. 2. I think the latter option might have created two Sent folders, one a subfolder of the other, so I copied and moved the messages, as you suggested.

Again, many thanks for your invaluable assistance!