The process of logging or storing a copy of a message in a queue is called journaling. Journal messages are stored in a queue called Journal.
Two types of journaling are available: source and target. Source journaling is the process of storing a copy of an outgoing message. It is configured on a message basis, and is therefore a property set by the sending application.
When source journaling is enabled for a non-transactional message, a copy of the message is placed in the source-journal queue of the sending computer either when the message arrives at the target queue or when the message reaches an MSMQ server that is one hop closer to the target computer. When source journaling is enabled for a transactional message, a copy of the message is placed in the source-journal queue of the sending computer when the message arrives at the target queue. A copy of the message is never stored in a source-journal queue on a server that forwarded the message.
Source journaling messages for MSMQ dependent clients are placed in the source-journal queue on the supporting MSMQ server. In MSMQ Explorer, the source-journal queue is displayed underneath the computer.
Target journaling is the process of storing a copy of incoming messages. It is configured on a queue basis. When target journaling is enabled, a copy of each incoming message is placed in the target-journal queue when the message is removed (read) from the target queue. A target-journal queue (Journal) is created for each queue when the queue is created. MSMQ Explorer displays target-journal queues under each public queue.
For information on enabling target journaling, see MSMQ Explorer Help. For information on enabling source journaling, see the MSMQ SDK.