outbox verifiedcritical
The sending queue
The one queue MailerQ reads. Everything to be sent — new mail, retries coming back, messages accepted over SMTP — arrives here.
In detail
Ten consumers with a window of a thousand messages each means the node claims up to ten thousand messages at once, and claimed messages are invisible to the rest of the cluster until they are acknowledged or the node dies. Its name comes from a routing key rather than an obvious directive, and the delay ladder inherits that name — both established by renaming it on the stand. For monitoring, its depth is the size of the backlog, and its consumer count is the proof that the engine is actually attached: a queue with messages and no consumers is a node that looks alive to systemd and is not working.
What happens if you get it wrong
Messages present, consumers zero.The engine is not reading — stopped, restarting in a loop, or consuming a differently named queue after a rename. The service can still report itself active.verified by experiment · inference