OutlookXP-Leave mail on server ?

You can adjust Outlook to leave mail on server to let other people at other PC-s to download the same mail. And Outlook “wisely knows” which mail was downloaded and it downloads only once each mail. However, if you transfer only .pst and other config files to another PC, each mail will be downloaded again, resulting duplicates. Where does outlook store this relevant information? And how could it be synchronized?