The following sections describe how the sendmail program works.
When a sender wants to send a message, the program issues a request to sendmail. The sendmail program then goes through the steps listed below, which are described in detail in the following sections.
Arguments are processed and the address is then parsed.
The message is collected.
The message is delivered.
If instructions are received from the mailer, the message is queued for retransmission.
If errors occur during processing, the message is returned to the sender.
If sendmail is called by means of the argument vector or is connected to through a pipe, the arguments are first scanned and ...