Just to clarify. I mapped to the file share location on the NAS using Windows Explorer creating a new drive letter. I've tested access to this NAS location by saving a test file to it. I've created a folder under Local Folders (in Thunderbird) pointing to the same location on the NAS and made this the archive location under Account Settings, Copies & Folders, Message Archives. However, each time I archive a message it's stored in a location under AppData/Roaming/Thunderbird/Profile/xxxxxx/Mail/Local Folder/XXXXXX.

J I've created a folder under Local Folders (in Thunderbird) pointing to the same location on the NAS and made this the archive location under Account Settings, Copies & Folders, Message Archives. However, each time I archive a message it's stored in a location under AppData/Roaming/Thunderbird/Profile/xxxxxx/Mail/Local Folder/XXXXXX.

How did you create this folder under local folders? Thunderbird has no facility to set a location for individual folders, only an account.

Hi Matt, thanks for your reply.

To be honest I can't fully remember how I did it originally - I'm trying to rediscover how I did it. Certainly, all the old archive files are on the NAS arranged by year and I could open them and look at the older e-mails - it was definitely working. I'm pretty sure the archive folders (one for each year) were under local folders.

What I did this time is I mapped a NAS drive to my PC so I end up with a new drive letter, in this case Z:. Then I right-clicked inbox and created a new folder under local folders using this drive letter and the file path on the NAS, say Z:\mail_archive. I then went to account settings and set the archive location to this Thunderbird folder. The folder has an archive icon. When I archive an e-mail it seems to be creating the archive on my C: drive under AppData\Roaming\Thurderbird etc.

I'm still experimenting here trying to figure out how I set it up the first time.

Most frustrating as my mailbox is full and I need to offload some content.

Again, thanks for any advice.

Regards, Kevin

what is the folder hierarchy on the nas looking like that contains the archives? The parent folder names might offer relevant information.

This is confusing, but it sounds like you simply had the whole Local Folders moved to the NAS on the old computer, but not on the new. Thunderbird wouldn't be storing mail moved there within your profile folder otherwise. And you cannot move only the archives to the NAS, you have to move the whole Local Folders.

Hello again

Yes it is confusing! I've now have a new profile due to the re-installation of Thunderbird on the new PC. I've relocated the profile folder from the default location on C: drive onto the NAS into a new folder using profile manager (separate to the existing folder that was used by the old PC and Thunderbird configuration). The folder/file structure of the new profile looks very different to the folder/file structure of the old arrangement - I wonder if this is related to the user of older Thunderbird versions or maybe something else? I have some of the old archive files on the NAS - how can I make them visible to the new profile? Thanks for your assistance. Regards, Kevin

Thunderbird stores mail using text files in mbox format with no filename extension. Accompanying .msf files are index files that can be removed, they're automatically re-created when not present. You may copy the desired mbox files from their location in the old profile folder into Local Folders in the new profile folder. Thunderbird will recognise them and show them under Local Folders in the folder pane the next time it's launched.

Hello again, thanks for all the info & help

So as previously stated, I now have my profile on my NAS and Thunderbird seems to be working OK.

I created a folder "Archive" under Local Folders and set this as the archive location in Account Settings, Copies & Folders. This created a folder Archive.sbd under Local Folders on the NAS. I then archived some old mail. In TB this created a series of year folders under the Archive folder. Using File Explorer showed series of corresponding file system folders of the form XXXX.sbd where XXXX is the year. In these folders are subfolders having the same names as the TB mail folders under my inbox - these are of the form NNNNNN.sbd where NNNNNNN is the name of the TB mail folder. In these are files, some with .msf extensions, some with no extension but with the same filename.

This all looks familiar as it is the same folder & file structure as my old archive files. So, I moved my old archive folders (of the form XXXX.sbd) into the same Archive.sbd folder on the NAS hoping that they would magically become visible in TB but sadly this did not happen - the old archives are not yet visible in TB.

Do you have any further wisdom to impart?

Thanks again for your assistance.

Regards, Kevin

You need an mbox file without filename extension or a .msf index file to make the corresponding folder appear in the folder pane in Thunderbird. An .sbd folder alone in the filesystem isn't enough by itself to cause the corresponding folder to appear in the folder pane in Thunderbird, and without that, Thunderbird won't show any other folders nested within the .sbd folder either.

Hello again, thanks for your help.

I've attached screenshots of some of the archive directories on the NAS.

Some of the .msf index files are there, however, for some of the older archive years the .msf files are missing for some reason.

Archive folders for 2025, 2024 & 2023 appear in Thunderbird under Local Folders, these were archived from the new install of Thunderbird on the new computer. The archives for the earlier years were the ones created from the install on the old PC that died. These folders were placed in the Archive directory on the NAS, however none of these currently appear as folders in Thunderbird archive under Local Folders.

2018 has a .msf file but does not appear as a folder in Thunderbird.

Do you have any further suggestions.

Again, thanks for your assistance.

Regards

IF you're adding Local Folders just double-click on your INBOX and you will see Add Folders. IF you're talking about Sub-Folders, just double-click on your Main Folder and you will see Add Sub-Folder.

After setting up your Folder structure go back and double-click on Title just above your IN-BOX and it takes you to your ACCOUNT. Make sure and direct items where to go.