~/Library/Thunderbird/Profiles/Profile name/ 

'''On Mac.:''' install Thunderbird and let it run to startup. It will then ask you to create a mail account. Do not make a new mail account. Exit/close Thunderbird. This will create a new Profile folder. '''On PC:''' make hidden files visible: http://kb.mozillazine.org/Show_hidden_files_and_folders In Thunderbird: Help > Troubleshooting information click on 'Show folder' a new window opens showing the contents of the 'Profile' folder - you should see all the Profile folders and files. these are the folders and files you need to copy. Close Thunderbird now - this is important. You need to copy all the files and folders you see in the Profile folder. Do not copy the profile folder itself - you need to copy the contents. Put them on a memory stick or external device. '''On MAC:''' Locate the new Profile name folder. ~/Library/Thunderbird/Profiles/Profile name/ The tilde character (~) refers to the current user's Home folder, so ~/Library is the /Macintosh HD/Users/username/Library folder. Paste the contents of the pc thunderbird profile folder into the new Profile folder on the mac. Overwriting any files currently in that profile folder. Open Thunderbird on MAC Do you see the emails etc.