XCON: Modification in X.400 Blind Copy Implementation

When an Exchange Server computer sends a message with blind copy (Bcc) recipients through an X.400 connector, the primary and copy recipients cannot see the Bcc recipients if they are all on an Exchange Server computer. However, if the recipients' mailbox is not on an Exchange Server computer, but on a third-party X.400 message transfer agent (MTA), they may be able to see the Bcc recipients.

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base: The English version of this fix should have the following file attributes or later:

Component: Information Store


Component: Information Store

Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 3.

The current implementation of the Bcc functionality in Exchange Server is modified by sending two different messages: one without Bcc recipients and one for the Bcc recipients. This guarantees that primary and copy recipients cannot see the Bcc recipients, no matter what remote third-party MTA is used.