A message routing system that allows applications at either end of the system to run as-is without modification. The system functions in a multithreaded environment and is capable of handling complex routing rules and message transformation. It is also capable of learning and executing new routing rules and message transformations in formats previously unrecognized by the system. The system enables precise and reliable logging of messages throughout processing and supports publication of enterprise-wide broadcast messages. The system further preferably employs cooperating inbound and outbound transport processes for consuming, routing, processing, safely storing and publishing messages in batches of logical units of work to ensure that the logical units of work are not lost in system transactions. The system also preferably utilizes a replay server for preserving and replaying messages that might otherwise fail to reach their intended destinations.