The following table describes the processes used by SMTP to deliver messages outside your Exchange organization.
|Sort messages and queue for delivery||Messages remain in the Queue directory. Recipients for each message are sorted in memory by domain so Exchange can send them as a group. This allows SMTP to optimize connections by delivering multiple messages in one session.|
|Determine whether the receiving server is ready to receive messages||The SMTP virtual server attempts to connect to the receiving mail server. If the receiving server is not ready, the message remains in the queue and delivery is attempted again at designated intervals up to a maximum number of attempts.|
|Send the message||After recipients are verified, the message is sent. After the
receiving server acknowledges the transmission, delivery is
complete. Delivery options are described below:
All outgoing messages, if not sent to a connector, can be sent to a smart host, which can then send them to remote recipients.
You can configure a list of trusted external DNS servers that your virtual server will use when processing messages addressed to non-local recipients. The virtual server will only use these DNS servers to look up remote addresses.
Related TopicsDeliver Messages Configure SMTP Delivery Options (on a connector)