The use of non-durable messages involves relaxing message delivery guarantees in order to achieve better performance.
See the documentation of the individual transport for details on how to enable non-durable messaging.
Individual transports interpret "non-durable" messaging with a custom approach dependent on how the underlying technology functions.
The default behavior of MSMQ is to use the concept of Store and Forward. In this approach, messages are stored durably on disk at the sender and then delivered by MSMQ to the receiver. When non-durable messaging is used, the MSMQ transport sends messages in Express Mode. The underlying setting that is used to achieve this is to set Message.Recoverable to
Non-durable messages are sent using RabbitMQ's non-persistent delivery mode, which means the messages are not persisted to disk by the broker.
The SQL Server transport has no support for this setting and it is ignored.
The Azure transports have no support for this setting and it is ignored.