In Thunderbird Help > Troubleshooting information click on 'Open Folder'

click on 'Mail' folder click on 'Local Folders' mail account make sure 'Size' column is enabled and all data is clearly visible. Post an image showing the contents of 'Local Folders'.

As you can see there is email in the folders but they do not show in the folder in Thunderbird

The size column was off the image, but there isn't any huge emails. Is there a size limitation with Tbd? Clearly I would expect even if there were size issues that the smaller mails would still load. The email volume is about 10GB of mail data.

Those eml filename extensions bother me. Whilst Thunderbird can use eml files, it doesn't store messages internally in eml format. So your export process has generated messages that Thunderbird can use but they haven't been imported properly.

Given that it appears that your export has generated eml files, I'd suggest using the ImportExportTools addon in Thunderbird to import them.

The import function would not work.

Any comments on how to get this working properly?

Assuming: you downloaded the 'ImportExportTools' .xpi file In thunderbird Menu icon > addons clicked on the gear icon and select 'Install addon from file' locate the .xpi file and click on 'Open' at prompt restart Thunderbird

To import the backup .eml files: Right click on a 'Local Folders' folder and select: 'ImportExporttools' > 'Import Messages' select backup folder where the *.eml files are stored select .eml file click on 'open'

Check the folder to see if email is there.

import messages is greyed out. So I cannot go farther forward.

HugoDrax said

import messages is greyed out. So I cannot go farther forward.

have you selected the folder you want to import the mail to? My guess is no.

Select a folder, right click on it and from that menu start you import. Then there can be no questions.

I selected the local folders as instructed above. Right clicked on it. Import messages is greyed out and cannot be selected. What else is there to do?

So how do I get my old email into Thunderbird? This is very frustrating. At this point it's starting to become like I should look for a different client.

REcheck which folder you are clicking on:

If you right click on the actual 'Local Folders' folder > ExportImportTools > you will find 'ImportMessages' greyed out.

If you create a new folder in the 'Local Folders' mail account and call it eg: 'Mail Import' and then right click on 'Mail Import' folder > ExportImportTools > you will find 'ImportMessages' should be available.

Well that does seem to work, BUT what a PITA to do this one folder at a time having to select that folder then select all the emails in it. Very, very time consuming.