For quite a few versions of OS X, you could find the email address history for Apple Mail in ~/Library/Application Support/AddressBook/MailRecents-v4.abcdmr. However, with Mavericks that file is no longer referenced. So if you are ever tasked with a manual migration of Apple Mail data, you will need to know where to find this updated file location. First we should note that Apple Mail is a sandboxed application. So it's resources live in a protected area in ~/Library/Containers. Drilling down a bit further, we will find ~/Library/Containers/com.apple.corerecents/recentsd/Data/Library/Recents/Recents. That is the file you will need to copy over. Secondly, Mavericks aggressively caches preferences so even after quitting and restarting Apple Mail, this change may not take effect. One easy way to get around this may be to restart. However, you can also kill a process called cfprefsd in Activity Monitory (or the command line) to clear this cache and Apple Mail should update its address history.