A queue name is always in a context of a specific Firebase account it is related to. It can also be a regular queue or a spam queue (for messages that are sent with a higher rate).
Producers
Queue is being filled by the directory messages service.
Consumers
Queue is being consumed by sender services.
Depending on the mode it is running (described by the SENDER_CONTAINER_SOURCE environment variable, which can be
either spam or can be unset for a regular mode), it will consume messages from different queues.