I have a user who uses Outlook 2013 to connect to Exchange 2010 over a high speed link. I got a call from him saying that all the emails he receives go directly to the Sync folder and they are all coming from one person and only one person. Nothing in his inbox.
I suspected that the issue could be a corrupt .ost file (32 GB in size) so I cleared the Exchange Cache and all worked fine.
Today I ticked this Exchange Cache back again and I could see that the folders where updating ( took a while about 10 minutes) and then with this box ticked everything works fine again.
The user has many mailboxes for other users in his outlook along with many other calendars.
The link speed is really high and that should not be an issue.
What could be the issue?