A method is disclosed by which network elements such as packet routers and packet switches guarantee the delivery of application layer messages within a network. According to one aspect, a first network element retrieves an application layer message from a source message queue, adds a message identifier to the application layer message, encapsulates the application layer message into data packets, and sends the data packets toward a destination application. A second network element intercepts the data packets, determines the application layer message from payload portions of the data packets, determines the message identifier from the application layer message, stores the application layer message in a destination message queue, generates an acknowledgement message that contains the message identifier, and sends the acknowledgement message toward a source application. The first network element intercepts the acknowledgement message and concludes that the application layer message within the matching message identifier was successfully delivered.