I decided to use Mail.app after using Thunderbird for years. When I use the import in Mail, it fails to import inbox items after May 2007. Then, I copied all inbox items into a folder in Thunderbird. When I import that folder into Mail, again 17 out of 282 items which are dated until May 2007. What do I have to do to fully import my mails? btw sent & messages in other folders are correctly imported.