Since it's a PST, I'm guessing it's a POP or IMAP connection. Most of the times I've seen "lost" email, they've either been moved to a different folder or archived. First thing I would do is check if there are any additional .PST files, particularly archive.pst files, in the folder that contains his regular .PST file. Otherwise, I'd check each folder (including the drafts, sent items, etc).

We all these missing messages from approximately the same time frame?

Hello Kaneto,

Yes most of the missing messages are from the same time frame.

However I have checked the Archive Folder and the messages don't appear to be in there; and furthermore the messages shouldn't have been archived due to not being "old" enough.

Thanks for your help and suggestions.

Kind Regards,

Davo