I am setting up users on new pc's. They currently run on Oulook 2010 with O365 and are moving to a NEW pc with Outlook 2013. The current mail runs through Office365. I would like to not have to re-download all the mail onto the new machine as some of the users mailboxes are very large. What is the process to move the mailbox from the one pc to the other and get the mail server not duplicate the mail. If i do an export and import onto the new machine i end up with duplicate mail (even though option to not import duplicates is selected) and this is because the mailbox on the new machine is empty and the mail server does not see the imported mail.