If there is no matching queue for the message, the message is dropped. RabbitMQ provides an AMQP extension known as the “Dead Letter Exchange”. This exchange which provides the functionality to capture messages that are not deliverable.

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channel.exchangeDeclare("some.exchange.name", "direct");

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Map<String, Object> args = new HashMap<String, Object>();

args.put("x-dead-letter-exchange", "some.exchange.name");

channel.queueDeclare("myqueue", false, false, false, args);

https://www.rabbitmq.com/dlx.html