message-only journaling

Message-only journaling creates a copy of all messages and the corresponding P2 message header data to and from users on a mailbox database and sends the message copy to a specified mailbox. The P2 message header contains only the message recipient data that the sender declared to the recipients. If an external message is received from the Internet, Exchange journals the P1 message headers. The P1 message header is the address information that is used by message transfer agents (MTAs) to route mail. By default, when message-only journaling is enabled, Exchange does not account for blind carbon copy (Bcc) recipients, recipients from transport forwarding rules, or recipients from distribution group expansions.