emails that were delivered by exchange but are missing from users inbox

1.) User1 says no email was received from the client between the following dates: 08/28/2013 to 09/11/2013
2.) Sender of email is external to our organization
3.) The other user's listed in the email string received the emails from Sender
4.) Checked the Message tracking center for said emails & found 21 that were delivered to User1's inbox between the dates previously mentioned
5.) Logged into User1's OWA to insure there were no Sync issues and did not find the emails in the inbox or deleted folder
6.) Logged into User1's outlook client and found no:

      Local failures

      Conflicts

      Server failures

7.) Also tried to recover emails from the Deleted Items Folder that may have been deleted on accident. Nothing.

8.) MS Support reviewed our exchange server for any possible resolution and they found no issue with config/routing/or the delivery of email.

      Support Ticket#: 113091610787503

9.) MS Support reviewed User1's laptop and could not find the emails exchange had reported that were delivered.

Basically MS Support could not explain why the emails were missing and somewhat blamed it  on end-user error by maybe accidental deletion. Which is something I would normally subscribe to but:

      1.) A 2 week long issue?

      2.) User1 is & has always been 100% professional in their conduct and duties. (AlsoNOT prone to lying).

      3.) Vendor(s) sometimes are NOT forthcoming about the short falls in their technology.

     

What I am looking for are others who may have suffered this type of issue and found a resolution. Please advise