Controls what the server should do if a message cannot be routed to any queue.
The Mandatory property controls what the server should do if the message can't be routed to any queue (either because it isn't eligible for any of the queues bound to the specified exchange because of how their bindings are configured, or because no queues are bound to the exchange in the first place). If True, the server will return the message. If False, the server will drop the message.
This property is not available in the Receiver.