Import Thunderbird address book from another computer

I will assume you use Windows. As a tip for the future, it's usually easiest when switching to a new computer to transfer the full profile. Doing that ensures that all accounts, settings, and addressbook get moved intact to new computer. Now, for your addressbook, here are general steps: # on old computer, go to c:\users\<yourid>\appdata\roaming\thunderbird\profiles # search each folder in the profiles folder for two files: abook.sqlite and history.sqlite. If you find more than one, usually the larger and more recently updated will be the latest versions. # copy both to external media # on new computer, start thunderbird and click to addressbook pane # in lower part of the screen is an import button. Do twice, once for each of the two files.