Without the Bulk Advanced Security tool, users can't open encrypted messages from their old mailbox in their new mailbox. Because a user's security file (.epf file) and security keys are associated with a user's mailbox, the old .epf file can't be used after the mailbox is moved. A new .epf file must be created for the mailbox by following the advanced security setup procedure.
To move encrypted messages from one site to another, users first move their messages to their .pst files and decrypt their messages by using the Bulk Advanced Security tool. After the messages have been moved to the new mailbox, they can be encrypted again with the Bulk Advanced Security tool. For more information on moving mailboxes between sites or recipient containers, see the Microsoft Exchange Server Administrator's Guide.