I have several email accounts that I manage using Microsoft Outlook 2003. One account behaves differently than the rest. The account is at Virginia Tech. Every time I restart Outlook and retrieve mail, it gets all mail in the VT mailbox instead of just the new ones. This doesn’t happen if I retrieve mail during an existing Outlook session, only if I restart Outlook. This is the only account where this has ever happened. They are all set to leave mail on server.
The fact that I only have this problem with one account suggests a server side problem but the fact that it only happens the first time I retrieve mail after starting Outlook suggests a client side problem.