<html> <head> <title>Postfix - the Big Picture</title> </head> <body> <h1><a href="big-picture.html"><img src="small-picture.gif" width="115" height="45"></a> Postfix - the Big Picture</h1> <hr> <img src="big-picture.gif" width="810" height="269"> <p> The figure shows the main Postfix system components, and the main information flows between them. Postfix system components are introduced in the <a href="receiving.html">Postfix anatomy</a> documentation. <p> <ul> <li>Yellow ellipsoids are mail programs. <li>Yellow boxes are mail queues or files. <li>Blue boxes are lookup tables. <li>Programs in the large box run under control by the Postfix resident <a href="master.8.html">master</a> daemon. <li>Data in the large box is property of the Postfix mail system. </ul> In order to keep the big picture readable the following elements were omitted: <p> <ul> <li>The Postfix <a href="commands.html">command-line utilities</a>. <li>The Postfix resident <a href="master.8.html">master</a> daemon. <li>The DNS lookups by the SMTP <a href="smtpd.8.html">server</a> and <a href="smtp.8.html">client</a> daemons <li>The <a href="bounce.8.html">bounce or defer</a> daemon and the flow of bounced mail. <li>The address rewriting and resolving requests by the SMTP server and by the local delivery agent. <li>The flow of mail forwarded by the local delivery agent. <li>The flow of <a href="basic.html#notify">postmaster notices</a> for protocol errors, policy violations, etc. <li>Triggers to alert the <a href="pickup.8.html">pickup</a> daemon and <a href="qmgr.8.html">queue manager</a> that new mail has arrived in the <b>maildrop</b> and <B>incoming</b> queues, respectively. </ul> <hr> </body> </html>