I have computer 1 with Office 365 Outlook - with email account. If I have a second computer and copy the .pst file from one computer to the other, I know that when I open Outlook all the existing emails will be there, calendar, etc. But if I have Outlook set to leave messages on the server, will the old messages be downloaded causing duplicates? I know that Outlook keeps an ID record of emails that are downloaded - but is this kept within the *pst file? If so then it should work that I can copy the *pst file and carry on without duplicates. I can understand that if I created a new blank account with nothing in it, then the old files would download...but will this still happen if I just copy & paste the email *pst account file across (keeping the name the same) - same Office 365....