If you care about reliability of the delivery, you can do a number of things: do a single call, wait for response and retry if needed, or store the messages in mnesia and only notify there's something to pick up (pull scenario with ack), or do a number of other possible things.

Lost messages are a fact of life really - the same will happen with any other system - either you persist the message and ack the reception on every stage or you risk dropping the queue.