To enable message journaling throughout a Microsoft Exchange Server site or organization, each server must be running Microsoft Exchange Server 5.5 Service Pack 1 and each server must be configured for message journaling.
You can configure message journaling at the server level, site level, or organization level. If you configure it at the site level, a message that is sent between two sites in the organization is saved twice: once at the sending site and once at the receiving site.
You enable and configure message journaling using Windows NT Server registry settings. Complete the following steps on each server. Each step is described in detail later in this document.