New Email from a Single User Disappears
 

I have a situation with one user only at a client site where new email from
one and only one sender reaches his mailbox but then disappears. This is
Outlook 2003 and Exchange Server 2003 SP2 on an SBS2003 server.

The messages are coming from a scanner that's on the same network segment as
the server and the client PC is. The Exchange SMTP server is configured to
allow connection and relay from this scanner's IP address. After a scan to
this user's address, the SMTP server log shows the messages coming in and
being accepted just fine.

If you use an Outlook 2003 profile with Cached Exchange Mode turned off, you
see the messages from this scanner in the InBox just fine. Same with
looking at the mailbox with OWA.

But if you use an Outlook 2003 profile with Cached Exchange Mode turned on,
you never see the messages from this scanner.

If you have two PCs running Outlook 2003 for this user at the same time, one
with and one without Cached Exchange Mode, you'll see the InBox message on
the non-cached mode PC for a minute or two and then it disappears. My
assumption is that the message disappears when the PC running in cached mode
does a synchronization.

The missing message never show up in Junk Email, Deleted Items, or any other
folder I can find.

I suspect some sort of rule that set to delete messages from the one sender
that this scanner uses, but I sure can't find any rules at all in the user's
Outlook.

In addition, there is another scanner configured the same way on the same
network segment but using a different sender email address. Scan emails
from that scanner come through and stay without any problem. The Sender
email addresses from each scanner are like and
, where Exchange accepts email for the company.com domain.

I'd love to have a hint from someone.

Thanks.