Folder Size Discrepancies

New Contributor



Why is there a discrepancy between the local and server folder size on the mailbox in Office 2016 (Office 365)?  I have made sure All items are being download, and full content rather than headers only.


I am migrating all these folders into a new mailbox, but I'm concerned something is being left on the server that I'm not seeing in Outlook.  There are hundreds of folders so I can;t go through them individually, but most of them are different.  It's not like one big folder missing.  




1 Reply

There can be a number of reasons for that, starting from the fact that storing data in the OST file is different from the method used to store the same items in the mailbox databases. You can review this thread for more detailed description: