Hi If you have a copy of your old profle folder, containing the .mab files, you should e able to copy just the .mab files to the new computer in place of the empty .mab files created when you started the new Thunderbird. You should look for any files with names ending .mab in your copy from the old computer. If you have some addresses in your new Thunderbird, you should export them first as you will need to re-import them. Some help here http://kb.mozillazine.org/Moving_address_books_between_profiles and where to look for the profile https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data Usually, unless you chose to store Thunderbird data elsewhere, it would be in C:\Users\<username>\AppData\Roaming\ Agnes