A bit confusing. You mention email folder and then reference email address. They aren't the same. If you are wanting to copy an email message folder to another computer, that can be readily done, but I'm unclear. Please clarify. Thank you.

actually I already solved this. I found the specific email profile file I needed to copy to the new computer. Of course I had to rename it before completing the transfer but it worked just fine. What I did discover is that the export feature does not work. It created a ZIP file that was supposedly 8 gb but trying to read the file resulted in a message saying the file was invalid and was actually empty.

That was when I decided to re-open the profile folder and finding the profile I needed under mail.

So I accomplished my goal of restoring that email profile to the new computer.

Yes,, David, that was what I meant and we can mark this question solved. Thanks.

I'm glad all is well. There is a warning when selecting the tools>export menu that states not to exceed 2 gb, but the message is rarely seen. I generally suggest copying the thunderbird folder, not the profile folder because that eliminates the issue of renaming the profile. For your future use, I share those steps here:

here is the info in brief steps:

1. ensure thunderbird is NOT running on old machine
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media
5. ensure thunderbird is installed on second computer and NOT running
6. enter %appdata% in search window on task bar and press Enter key
7. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
8. start thunderbird and all should be there