To enhance performance, all message transactions are written first to log files and memory, and then to the database file. Like any ESE database, the queue database uses log files to accept, track, and maintain data. By default, this queue database is located on the transport server at %ExchangeInstallPath%TransportRoles\data\Queue. Regardless of destination, all messages that have unreachable recipients reside in this queue.Įvery Mailbox server or Edge Transport server has only one Unreachable queue.Īll the different queues are stored in a single ESE database. Typically, an unreachable destination is caused by configuration changes that have modified the routing path for delivery. For more information about the categorizer and the transport pipeline, see Mail flow and the transport pipeline.Įvery Mailbox server or Edge Transport server has only one Submission queue.Ĭontains messages that can't be routed to their destinations. After categorization, the message is moved to a delivery queue or to the Unreachable queue. The categorizer retrieves messages from this queue and, among other things, determines the location of the recipient and the route to that location. On Edge Transport servers, messages are typically received by a Receive connector, but the Pickup and Replay directories are also available. On Mailbox servers, messages are received by a Receive connector, the Pickup or Replay directories, or the Mailbox Transport Submission service. Messages in the Submission queue are either waiting to be processed, or are actively being processed. Holds messages that have been accepted by the Transport service, but haven't been processed. For more information, see Shadow redundancy in Exchange Server. Shadow queues hold redundant copies of messages while the messages are in transit. Messages remain in the poison message queue until they're manually resumed or removed by an administrator.Įvery Mailbox server or Edge Transport server has only one poison message queue. Messages in the poison message queue are never automatically resumed or expired. If the poison message queue contains no messages, then it doesn't appear in the queue management tools. The poison message queue is typically empty.
#LOCAL QUEUE STUCK MDAEMON SOFTWARE#
The messages may be genuinely harmful in their content and format, or the messages might have been the victims of a poorly written transport agent or a software bug that crashed the Exchange server while it was processing the otherwise valid messages. Isolates messages that contain errors and are determined to be harmful to Exchange after a server or service failure. For more information, see Delivery Agents and Delivery Agent Connectors. Non-SMTP destinations also use delivery queues if the destination is serviced by a Delivery Agent connector. For more information, see the NextHopSolutionKey section later in this topic.Īll messages are transmitted between Exchange 2016 and Exchange 2013 servers by using SMTP. On Mailbox servers, there's a queue for every unique destination as indicated by the NextHopSolutionKey property. On Edge Transport servers, there's a queue for every unique destination SMTP domain or smart host.
The queue expiration time is controlled by the QueueMaxIdleTime parameter on the Set-TransportService cmdlet. Holds messages that are being delivered to all internal and external destinations.ĭelivery queues are dynamically created when they're required, and are automatically deleted when the queue is empty and the expiration time has passed. Mailbox servers and Edge Transport servers The following types of queues are used in Exchange 2016 and Exchange 2019, which are the same as Exchange 2013: For more information, see Procedures for queues and Procedures for messages in queues.
You can also perform actions that modify queues or the messages in queues. You can use these interfaces to view the status and contents of queues and detailed message properties. You can manage queues and messages in queues by using the Exchange Management Shell and Queue Viewer in the Exchange Toolbox. Like all previous versions of Exchange, a single Extensible Storage Engine (ESE) database is used for queue storage. Mailbox servers and Edge Transport servers are called transport servers throughout this topic. Queues exist in the Transport service on Mailbox servers and on Edge Transport servers. In Exchange 2016 and Exchange 2019, queues hold messages before, during, and after delivery. Each queue represents a logical set of messages that the Exchange server processes in a specific order. A queue is a temporary holding location for messages that are waiting to enter the next stage of processing or delivery to a destination.