Sort messages and queue for delivery.

Messages remain in the Queue directory. Recipients for each message are sorted by domain so the SMTP service can send them as a group. This enables the SMTP service to optimize connections by delivering multiple messages in one session.

Determine whether the receiving server is ready to receive messages.

The SMTP service tries to connect to the receiving mail server. If the server is not ready, the message remains in the queue and delivery is tried again at designated intervals, up to a maximum number of attempts. These intervals are the retry settings. You set them on the Delivery tab.

Send the message.

After recipients are verified, the message is sent. After the receiving server acknowledges the transmission, SMTP delivery is finished. Consider the following delivery options:

• If you have enabled Transport Layer Security (TLS) for remote delivery, the SMTP service encrypts all outgoing messages. You can also enable or disable this function for a specific remote domain. You set TLS encryption in the Outbound Security dialog box, which you access by clicking Outbound Security on the Delivery tab.
  
  
• All messages for remote domains can be sent to a smart host, which can then send them to the recipients. You designate the smart host in the Advanced Delivery dialog box, which you access by clicking Advanced on the Delivery tab.