When all recipient addresses are parsed and routed, the Enqueuer component applies the Server-Wide Rules to the message. Then it passes the message to the modules specified with the Router component.
Communication modules do not process E-mail messages immediately, but enqueue them into the module-specific queues. The SMTP Module creates and maintains a queue for each Internet domain, the Local Delivery Module creates and maintains a queue for each local Account, etc.
The Enqueuer component can enqueue messages:
Most of the internal components enqueue messages asynchronously, as they cannot do anything useful if a message is rejected with the Enqueuer component. The components receiving messages directly from users or remote systems (SMTP, MAPI, WebMail, XIMSS) try to enqueue messages synchronously, so if a message is rejected with the Enqueuer component, the submitting agent (a user or a remote system) can get an error message.
Use the WebAdmin Interface to configure the Enqueuer component. Open the Queue page in the Settings realm.
Enqueue Log: Use this setting to specify what kind of information the Enqueuer component should put in the Server Log. Usually you should use the Failures (file system error reports) level. The Enqueuer component Log records are marked with the ENQUEUER tag.
Enqueue Asynchronously: Use this option to specify when the asynchronous Enqueuer mode should be used:
Processors: Use this setting to specify the number of Enqueuer processors (threads). If the asynchronous Enqueuer mode is not used, the Enqueuer threads are needed only to enqueue existing messages after the Server restart, and to enqueue messages generated with the internal Server component, so