I will try to explain to the best of my ability.

We are a Non-Profit blood bank, who on occasion will send out an email
to all donors who provided their email address to us.

We use Exchange 2003.  The email addresses are stored as Contacts in an
Exchange Public folder.  There are aprox. 3000 email addresses stored
and categorized by blood type.  When a certain blood type is running
low, we can send an email to all donors with that blood type to request
that they come in and donate.

The emails are sent by authorized users in the domain that have Send On
Behalf Of permissions to the Company email box.  Each one of them has
the Company email account added to Outlook 2k3, and they will place the
blood type contact in the BCC field, and send it on it's way.

Recently we have been experiencing a rash of bounced back emails that
we cannot locate in the entire list of Public folder Contacts.  The
fact that the emails are coming back as undeliverable is not really a
problem.  The problem exists that we would like to locate these emails,
so that we can see a name associated with it, and contact the donor
with the mail issue.  When we search the contacts, it comes up with
nothing.  We cannot see these emails anywhere in the list of contacts.
I have searched the local machine of the users who send these emails,
only to find nothing.  I ahve searched the Exchange Public folder
Contacts, and still find nothing.

Does anyone know where these emails are being stored?  Is there any
additional places I should search to find them?

Any and all help would be extremely appreiciated.

Thank you

Ben