[Skunkworks] Lost E Mails in Outlook 2003 Connected to Exchange 2003

Hi all, I have a user who has lost her sent mails plus a few mails in her inbox. The user claims she has not deleted the mail from her mailbox and also she has not archived her mail (auto archive is turned off). The organization uses EXCHANGE 2003 as the mail server and the user has outlook 2003 as the client. I have tried the recover deleted items option under the tools tab but nothing has come up. Also she has no .pst file or archived file on her machine. Kindly assist me on how to recover her mails and what could have caused her mails to get lost. Regards James