Reliable messaging refers to the ability of a sender to deliver a message once and only once to its intendedreceiver.
可靠的消息传递是指发送方向它所期望的接受方传递一次并且只传递一次消息的能力。
2
If a FWD element that contains one or more via elements is present, the receiver should remove and inspect the top via subelement of FWD and verify that it is the intended recipient of the message.