Processing outgoing mail

Mail and Messaging Guide
Chapter 4, Managing mail with MMDF

Outgoing mail starts when the user invokes an MUA, such as mail(C) or scomail(XC) to compose a mail message, or when incoming mail is accepted for routing through the local host to another destination. How MMDF handles outgoing mail is illustrated in Figure 4-3, ``Outgoing mail''.

Figure 4-3 Outgoing mail

A mail message is sent using this procedure:

When the user sends the messages for delivery, the MUA ensures that the message has the required mail headers.
The MUA transfers the message to execmail, which sends it to submit(ADM). Alternatively, submit may accept the incoming mail from a channel.
The submit program builds the fully qualified domain name for the recipient by mapping the information in the ``To:'' field with the information in the domain tables.
submit then looks up the fully qualified domain name in the channel tables to determine the appropriate channel through which to send the message, and places the message in the appropriate channel queue.
The deliver(ADM) program, which runs periodically (by default, deliver runs every 10 minutes), transfers the message from the channel queue to the appropriate channel program, which routes it to its destination.

For example, you send a message with this ``To:'' line:

   To: andrei@mynet.com

The submit program looks in the appropriate MMDF configuration table for mynet and builds the fully qualified domain name; for example:

   volga.mynet.com

Now, submit determines the appropriate channel to use to send the message. In this example, all messages in the mynet.com domain are sent to the outside world on the UUCP channel, so submit puts the message in the UUCP channel queue. Then deliver picks up the message and passes it to the channel program. The channel program transfers the message out of the MMDF mail system and into the UUCP subsystem where it is queued and sent via UUCP.