Managing transport queues
A queue is a temporary storage location for messages in Exchange before they proceed to the next step of processing or delivery. In Exchange 2013/2016, the following types of queues are used:
Persistent queues: They exist on every transport server in the organization and are of the following types:
Submission queue: Categorizer uses this queue to collect all the messages that need to be resolved, processed, and routed by the different transport agents
Unreachable queue: This queue is for messages that Exchange cannot route to the destination
Poison message queue: This queue holds messages that the Exchange system thinks is harmful for the environment after a crash of the transport server or service
Delivery queues: These queues and dynamically created and removed when empty and is used to hold messages in transit, which are in the process of being delivered to either local or remote destinations using the SMTP protocol.
Shadow queues: They hold redundant copies of a message...
