This routine returns a pointer to a NULL terminated string containing the MTA local postmaster address. This address is suitable, for instance, for inclusion in the From: header line of notification messages as shown in the code example for this routine.
It is usually not a good idea for programs to send mail to the postmaster’s address. In many situations, sending mail to the postmaster when failures occur can lead to mail loops if the mail sent to the postmaster itself fails, and generates a message to the postmaster, which then fails, and generates yet another message to the postmaster, and so on.
On a successful completion, the address of the string buffer containing the postmaster’s address is returned using the address call argument. That same address is also returned as the return status.