Outlook 2003 and Cached Exchange Mode

When Outlook 2003 is configured for Cached Exchange Mode on a corporate network with Exchange 2003, are you actually viewing the contents of the local mailbox (OST) when online or the server folder? The reason I ask is, if I go to a folder in my mailbox on a machine where it is configured for CEM, select Properties – Synchronization – Filter – Advanced, then set up a rule to filter Received items on or before a certain date the mail items matching that criteria then disappear from the folder. If I go to a different machine that does not have that same mailbox configured for CEM I am able to see the filtered email in that folder.

Thanks!