Message journaling adds processing overhead to the Microsoft Exchange Server and increases network traffic. Use Windows NT Performance Monitor after enabling message journaling to ensure that your system can handle the additional load. You may need to upgrade your hardware or balance system resources.
Note The performance enhancements in the message transfer agent (MTA) in this service pack should help balance the processing overhead of message journaling.
The mailbox, public folder, or custom recipient that receives the message copies must always be available, or message journaling will fail. Depending on message volume, you might need to set up the mailbox or public folder on a dedicated Microsoft Exchange Server computer within the site.