I don't know Macs, but if thunderbird is still on the old machine, try this: - click help>troubleshootinginformation - scroll down to 'profile folder' in left column and click 'open profile' - Now exit Thunderbird and you should be in the File manager for mac, listing the profile. - if all you want are the message folders, but not the full profile, they will be in either the Mail folder for POP accounts or Imapmail folder for IMAP accounts. If you want the entire profile, back up one folder. the folder name would probably end in 'default' or 'default-release'

- if you want the full profile, complete with account info and other settings, copy the profile folder to the same place on the new computer, again with thunderbird not running.