I had a user with a mailbox size of 500mb on both the server and the local PC folders. However, the user was reporting that there were many emails missing.
I was going to attempt a rollback of the mailbox, so I exported the existing (500mb) mailbox to a .pst as a backup. However, when I exported this mailbox, the .pst size was 2gb. When I re-imported this .pst on the user's local machine, all of the missing emails were imported back in.
There were no filters applied, the emails werent archvied/deleted/moved and this wasn't a local pc issue as the mails were also missing from OWA view.
Anyway, this problem is essentially resolved, but its nagging me as to why this might have happened. Any ideas?