Exception Rules are intended to be used to override the General Settings, by either identifying message traffic to specifically journal or specifically ignore.
Each Exception rule can have as many as 4 variables to define and identify the target email traffic. These variables include To/From addressing components, subject text, attachment name or type, embedded URLs, and message body text. Each defined rule is compared to the eligible mail items and when a match is made, the mail item is either added to the journal stream or is ignored, as specified by the rule.
Exceptions should be primarily used to identify mail traffic to OMIT from the journal process, such as email alerts, scheduled reports, trusted information exchanges (technical forums) and selected users.
Exceptions CAN be used to select email traffic for journaling, but should only be used in this fashion if general journaling of Inbound SMTP, Outbound SMTP or Internal Exchange Mail is NOT specified in the General Settings properties.
Message Journaling - online Help
Message Journaling Reports - online Help