Mac Mail user gaining non-granted access to Exchange 2003 contact informati

One of my Mac users has been able to search public folders that he should not have access to while using Mac Mail. This was not intentional on his part – the information just came up in the result of a search that he did from within Mac Mail.

I cannot figure out how this has happened.

Has this happened to anyone else? Any suggestions as to where to look to correct it?

I have checked double-checked the permissions on the public folders and cannot see any problem that would have allowed this to happen.