This variable generates verbose mail routing statistics per destination. If you set RouterEnableMailByDest=1, the router maintains statistics for each mail routing destination, which include the last successful/unsuccessful transfer time, total number of messages routed, and the total number of failures. These statistics may be useful when attempting to troubleshoot routing-related problems.

Valid Values are:
0 - No destination based statistics are generated by the router.
1 - Router maintains statistics for each mail routing destination, which include the last successful/unsuccessful transfer time, total number of messages routed, and the total number of failures.