The advanced queuing engine defines and manages queues for message delivery, such as domain queues and link objects that you can query for transport information. Once the advanced queuing engine receives an SMTP message, it relays the message to the categoriser. The categoriser returns the message after it determines the destination. The advanced queuing engine then queues the message for eventual delivery, taking into account remote routing information from the routing engine. Lastly, it delivers the message to either the local Web Storage System driver or the local SMTP stack.