Knowledge base
rabbitmq-addresscriticalWritten by the HubdirectiveAMQP address of the broker that carries the mail: host, credentials and virtual host in one string.rabbitmq-outboxcriticalWritten by the HubdirectiveRouting key used when a message is published for sending — and, on a stock configuration, also the name of the queue the engine reads.rabbitmq-persistentcriticalWritten by the HubdirectiveWhether messages are stored on disk by the broker, so that mail in the queue survives a broker crash — off by default, and deliberately so.rabbitmq-queuecriticalWritten by the HubdirectiveName of the queue MailerQ reads messages from; when it is not set, the engine falls back to the queue named by rabbitmq-outbox.rabbitmq-consumersimportantWritten by the HubdirectiveHow many threads read from the consumed queue in parallel.rabbitmq-declareimportantWritten by the HubdirectiveWhether MailerQ declares the queues and exchanges it needs at start-up, or expects them to exist already.rabbitmq-durableimportantWritten by the HubdirectiveWhether queues and exchanges declared by the engine are durable, meaning the broker recreates them after a restart.rabbitmq-exchangeimportantWritten by the HubdirectiveExchange every published message goes to; empty means RabbitMQ's default exchange, where the routing key is simply the queue name.rabbitmq-inboximportantWritten by the HubdirectiveWhere a message accepted by the built-in SMTP server is published; ships pointing at the sending queue, so accepted mail goes straight out.rabbitmq-qosimportantWritten by the HubdirectiveHow many messages one consumer thread may hold unacknowledged at a time.rabbitmq-lazyWritten by the HubdirectiveDeclares queues as lazy, so the broker moves messages to disk as they arrive instead of holding them in memory.rabbitmq-maxpriorityWritten by the HubdirectiveHow many priority levels the consumed queue supports; zero means priorities are not used at all.rabbitmq-publishersWritten by the HubdirectiveHow many threads publish results back to the broker.delayed-declaredirectiveWhether the delay-step queues are declared by the engine at start-up.delayed-exchangedirectiveExchange used when publishing a message into a delay step; defaults to the main result exchange.delayed-lazydirectiveDeclares the delay steps as lazy queues, so waiting messages are written to disk.delayed-replytodirectiveExchange a delayed message is sent back to when its wait is over.delayed-routingkeydirectiveRouting key used when a message is published into the ladder.delayed-typedirectiveWhether the delay steps are declared as classic or quorum queues.rabbitmq-encodingWritten by the HubdirectiveWhether messages the engine publishes are compressed, and with what.rabbitmq-flushdirectiveHow many messages are loaded at once while the engine is draining a queue.rabbitmq-minqosdirectiveThe smallest window the engine will shrink to when it reduces prefetch under pressure.rabbitmq-refuseddirectiveWhere messages the SMTP server refused are published, if they are to be kept at all.rabbitmq-throttledirectiveHow many messages may be written to the broker socket at the same time.rabbitmq-unroutabledirectiveWhere a published message goes when the exchange has nowhere to route it.temporary-declaredirectiveWhether the exchange for temporary queues is declared at start-up.temporary-durabledirectiveWhether the exchange for temporary queues is declared durable.temporary-exchangedirectiveExchange the engine binds each temporary queue to when it creates one.temporary-typedirectiveWhether temporary queues are declared classic or quorum.Where queue names come from, and what inherits themimportantWritten by the HubmechanismThe consumed queue takes its name from rabbitmq-queue, or from rabbitmq-outbox when that is absent — and the entire delay ladder is named after it.Make sure the telemetry has exactly one readerimportantprocedureResult queues are consumed, not read: a second reader does not duplicate the data, it splits it.outboxcriticalqueueThe one queue MailerQ reads. Everything to be sent — new mail, retries coming back, messages accepted over SMTP — arrives here.(default exchange)Written by the HubqueueRabbitMQ's built-in exchange, where a routing key is simply a queue name — which is why MailerQ's routing keys read like queue names.inboxWritten by the HubqueueWhere mail accepted over SMTP is published — pointed at the sending queue by default, so accepted mail simply leaves.refusedqueueWhere messages the SMTP server rejected would be kept, if anyone wanted them.unroutablequeueCatches messages an exchange could not route anywhere.prioritymessage propertyPriority within the sending queue — ignored unless the queue was declared with priority support.Hold messages and release them laterWritten by the HubtoolA standalone delay mechanism, of the kind MailerQ's own outbox ladder already implements.Turn queue messages into HTTP callstoolA bridge from the broker to a webhook — the shape most third-party systems expect.Declare the broker topology from a fileWritten by the HubtoolBuilds a RabbitMQ topology from a description, instead of by hand or by letting the engine declare it.Pick up files from a directory into the brokertoolThe file-drop road into MailerQ, for senders that cannot speak SMTP or AMQP.Call an HTTP endpoint for each messagetoolA generic HTTP caller driven by the broker.