+[thumbnail="pmg-gui-tracking-center.png", big=1]
+
+Email processing is a complex task and involves several service
+daemons. Each daemon logs information to the syslog service. The
+problem is that a server analyzes many emails in parallel, so it is
+usually very hard to find all logs corresponding to a specific mail.
+
+The Tracking Center simplifies the search for
+emails dramatically. We use highly optimized and safe Rust footnote:[A language
+empowering everyone to build reliable and efficient software.
+https://www.rust-lang.org/] code to search the available syslog data. This is
+very fast and powerful, and works for sites processing several million emails
+per day.
+
+The result is a list of received mails, including the following data:
+
+[cols="s,5d"]
+|====
+|Time | Timestamp of first syslog entry found
+|From | Envelope 'From' address (the sender)
+|To | The email receiver address
+|Status | Delivery status
+|Syslog | The corresponding syslog entries are shown if you double
+click such an entry or if you press the '+' button on the left
+|====
+
+To narrow the search down further, you can specify filters and set
+a 'Start' and 'End' time. By default, the start time is set to the
+last hour. If you still get too many entries, you can try to restrict
+the search to a specific sender or receiver address, or search for a
+specific text string in the logs ('Filter' entry).
+
+NOTE: Search is faster if you use a shorter time interval.
+
+The 'Status' field summarizes what happened with an email. {pmg} is a
+mail proxy, meaning that the proxy receives mails from outside,
+processes them and finally sends the result to the receiver.
+
+The first phase is receiving the mail. The proxy may reject the mail
+early or accept the mail and feed it into the filter. The filter
+rules can then block or accept the mail.
+
+In the second phase, accepted mails need to be delivered to the
+receiver. This action may also fail or succeed. 'Status'
+combines the results from the first and second phase.
+
+[options="header",cols="2s,1d,5d"]
+|====
+|Status |Phase |Description
+|rejected |1 | Email rejected (for example, the sender IP is listed on an IP blacklist)
+|greylisted |1 | Email temporarily rejected by greylisting
+|queued/deferred |1 | Internal email was queued, still trying to deliver
+|queued/bounced |1 | Internal email was queued but not accepted by the target email server (for example, user unknown)
+|queued/delivered |1 | Internal email was queued and delivered
+|quarantine |1 | Email was moved to quarantine
+|blocked |1 | Email was blocked by filter rules
+|accepted/deferred |2 | Email accepted, still trying to deliver
+|accepted/bounced |2 | Email accepted, but not accepted by the target email server (for example, user unknown)
+|accepted/delivered |2 | Email accepted and delivered
+|====
+
+[[postfix_queue_administration]]
+Postfix Queue Administration
+----------------------------