User needs to using Outlook365 app (not Office 2013 -2019) with an O365 E3 license.


  1. Before starting the Archives need to be closed out from Outlook.  This can be done in the app (right click on Archive name and pick 'Close ......') and then restart Outlook - or done in Control Panel - Mail - Data Files -  and removing the pst archive data files from the profile. 
  2. In Outlook - Click File - Open & Export - Import/Export Option
  3. Pick this option:
  4. Chose PST Option:
  5. Pick the PST from local computer then use the Do not import duplicates:
  6. You will need to change the Import Items into the same folder dropdown so you are choosing the Online Archive option for the account: 
  7. Click Finish - while the export is working - Outlook app will NOT be available to use.  User will need to use Web Mail (https://outlook.office.com) until the export is completed.  Depending on the size of the original PST file - it could take more than an hour.  If you can set this to start right before leaving to go home, and then lock the pc but don't log out so it can finish processing.