I believe ROBROS is not refering to actual corrupt files per se (PST files) but mailbox "items"/messages, that are listed as corrupt in the mailbox backup. The mailbox backup uses the MAPI protocol transport provided by the MAPI client installed on the Backup server. So BE is actually just reporting read problems that the MAPI client itself (usually Outlook) is running into. And before anyone mentions that they can open these types of files/e-mails in Outlook just fine, consider the last time Outlook EVER reported a failure to read a message in your mailbox. It almost never does b/c it supresses all such error messages and just shows you what it can. Backup software does not have that luxury and must report all problems presented by the MAPI client for safety sake. Check out these mail items, in all likelihood they have some weird formatted attachment or the attachment has been stripped by an anti-virus program or some other mechanism. If the item seems fine, try forwarding it to another mailbox and see if it fails there too. If not, delete the original and forward it back, it could have just been that that particular placeholder (reference) in Exchange was bad.
These corrupt issues can be very time consuming, so you might want to just consider unchecking these items as suggested and simply copy and paste that section of the job log into an e-mail to that user so they can take their own actions to protect those particular e-mails or to clear them out. And if its an excessively personal e-mail for that employee then just get 'em fired, that'll fix it! (just kidding).
