- the Big Picture
The figure shows the main Postfix system components, and the main
information flows between them. Postfix system components are
introduced in the Postfix anatomy
In order to keep the big picture readable the following elements were omitted:
- Yellow ellipsoids are mail programs.
- Yellow boxes are mail queues or files.
- Blue boxes are lookup tables.
- Programs in the large box run under control by the Postfix
resident master daemon.
- Data in the large box is property of the Postfix mail system.
- The Postfix command-line utilities.
- The Postfix resident master daemon.
- The DNS lookups by the SMTP server
and client daemons
- The bounce or defer daemon and the
flow of bounced mail.
- The address rewriting and resolving requests by the SMTP server
and by the local delivery agent.
- The flow of mail forwarded by the local delivery agent.
- The flow of postmaster notices
for protocol errors, policy violations, etc.
- Triggers to alert the pickup daemon
and queue manager that new mail has arrived
in the maildrop and incoming queues, respectively.