1. In an application integration system that communicates messages between applications, a computer-implemented method for transmitting electronic messages that preserves a message format native to both a sending application and at least one receiving application, the method comprising: receiving a message from the sending application, the message having a message format used by the sending application; wrapping the message in a markup language file envelope; routing the markup language file envelope with the message through the application integration system; unwrapping the message from the markup language file envelope; and transmitting the message according to the message format to the receiving application.