danbos wrote:

I receive the following message when I attempt to open an email with a
digital signature attached.

"Cannot open this item. Your Digital ID name can not be found by the
underlying security system."

The email server is Exchange Server 2003 Enterprise edition and I am
using Outlook 2003 for the client.

This means that the person who sent you the message encrypted that message
with a public key that belongs to someone other than you. They must use
your public key, which means you must have a certificate, when encrypting a
message.
--
Brian Tillman