If the old pc is accessible, this will import everything: Here is the link for moving a profile in Windows when installed in default location:

https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

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

Hi David,

While some of your info is helpful, I have more specific questions. The old pc is not accessible, but I do have the hard drive which contains all the Thunderbird profile files, and I can connect this drive to my new pc which has not yet arrived. The old pc was running windows 10, and the new one will be running windows 11.

The laptop I tried to do the import with initially is also running windows 11, and it did not seem that the user app data is in the same place as in windows 10. Also, when I tried installing Thunderbird on the laptop, it took me to the Microsoft store to download it as an app. Is that something I should avoid? Should I be downloading the install file directly from Mozilla for my new machine? Once I have this resolved I will attempt to manually copy the old pc profile to the new instance of Thunderbird and hopefully that will work. Please let me know if you have any insights. Thanks, Gary