E-mail delivered to local store in Exchange... but not appearing in mailbox

I am tracking a Blackberry Activation mail from RIM which appears to have been delivered successfully, but is not in the mailbox is has been delivered too.

First it hits our Barracuda spam filter, which approves it and passes it through (untouched) to our Exchange 2003 server. Message tracking reports that "SMTP Store Driver: Message Delivered Locally to Store to user.name@company.co.uk"

However, it's not in the mailbox. It's not anywhere in the mailbox in any folder, nor is it in the Recover Deleted Items folder.

Our Barracuda filter keeps a copy of all incoming mail, so I tell it to redeliver this e-mail, along with another unrelated e-mail. Message tracking reports both successfully delivered, yet waiting in Outlook I only see the unrelated message appear, the Blackberry Activation mail never arrives.

There are no Send/Receive errors in Outlook, nor does the user have any rules enabled. Junk mail is setup using the defaults and the mail has not been filed as junk (I did an Advanced Find on all folders) and it hasn't been deleted either.

What the heck is going on? Other users have received these same e-mails just fine.

If message tracking says it was delivered locally to the mailbox, then it was delivered.

You should check to see if anything else could have affected the message after it was delivered.  For instance, check if there is any client-level antivirus or antispam running on the client desktop that interact with Outlook.

Have you enabled the DumpsterAlwaysOn registry key, and then checked "Recover Deleted Items" for both Inbox and Deleted Items?

Its been suggested that I'm not seeing it simply because the BES is immediately processing the mail.

I am seeing a very similar situation on my exchange 2003 system.

We have a network scanner that sends the PDF document in email. I have 1 user who does not get the mail in their client, however there are no returned message failures nor are there any indications that there was a problem. System Manager shows the mail is being delivered to the mailbox store for the user.

This mail is routed internally, does not go through our barracuda spam firewall.

Is sent from network scanner using an authenticated connection to the exchange smtp service. Delivered to a mailbox on the exchange server it was sent from.

The client does not have any filter rules and junk mail is set to low.

User can receive mail from the account that sent the scanned PDF attachment when I log into Outlook with that user, but it does not show that her client gets the message when sent from the scanner.

any ideas?