I am moving to a new laptop and want to take all Thunderbird mail, accounts and settings with me. Where does Thunderbird keep it all?

Everything is in your profile folder. To open it:

1. In Thunderbird choose Help > More Troubleshooting Information.
2. Under Application Basics click Open Folder next to Profile Folder.

Close Thunderbird, then copy the entire profile folder to an external drive. On the new laptop install Thunderbird, open it once, close it and in Help > More Troubleshooting Information find the new profile folder. Replace its contents with the copied files, or use the Profile Manager (thunderbird.exe -P) to point to the copied profile.

Copy the full folder, not only the Mail folder, because accounts, filters, address books and passwords live in other files inside the profile.

Copied the entire profile and it opened with everything on the new laptop. Thanks.