Installation und Konfigurationsdateien von Postfix 3 unter CentOS 7.x

Bild: Postfix-Logo
Nachdem wir uns einen grundlegenden Überblick über Postfix verschafft haben, werden wir uns nun eingehend mit der Installation und Grundkonfiguration unseres Postfix 3-MTA1) beschäftigen.

Die Neuerungen und größten Änderungen zu der bisherigen Version 2.x finden sich in der von Wietse Venema bereitgestellten Dokument.

Die wichtigsten Änderungen (in keiner bestimmten Reihenfolge) sind:

  • SMTPUTF8-Unterstützung für internationalisierte Domainnamen und Adresslokalteile gemäß RFC 6530 und verwandten Dokumenten. Die Implementierung basiert auf dem von Arnt Gulbrandsen eingebrachten und von CNNIC gesponserten Code. Der SMTPUTF8-Support ist in Arbeit; er wird voraussichtlich während des Entwicklungszyklus von Postfix 3.1 abgeschlossen sein. Eine Zusammenfassung der Einschränkungen findet sich SMTPUTF8_README.
  • Unterstützung für Postfix dynamisch verknüpfte Bibliotheken und Datenbank-Plugins. Die Implementierung basiert auf Code von LaMont Jones für Debian Linux.
  • Ein OPT-IN Sicherheitsnetz zur selektiven Übernahme neuer Postfix-Standardeinstellungen. Wird nichts besonderes konfiguriert, bleiben die alten Postfix-Standardeinstellungen in Kraft.
  • Unterstützung für Operationen auf mehreren Lookup-Tabellen. Der Datenbanktyp pipemap:{map1,map2…} implementiert eine Pipeline von Nachschlagetabellen, bei der das Ergebnis einer Nachschlagetabelle zu einer Abfrage für die nächste Tabelle wird; der Datenbanktyp unionmap:{map1,map2,…} sendet dieselbe Abfrage an mehrere Nachschlagetabellen und verknüpft deren Ergebnisse.
  • Unterstützung von Pseudotabellen, die einfache Dinge einfach zu implementieren machen. Die inline:{key1=value1,key2=value2,…} Tabelle vermeidet die Notwendigkeit, eine externe Datei für nur wenige Elemente zu erstellen; und die randmap{value1,value2,…} Tabelle implementiert eine Zufallsauswahl aus den angegebenen Werten.
  • Tabellengesteuerte Transformation von DNS-Lookup-Ergebnissen sowie von Statuscodes und Nachrichten von Zustellern. Typischerweise würde man eine PCRE-Tabelle verwenden, um problematische DNS-Antworten zu beheben oder die Behandlung von Lieferfehlern zu beheben. Siehe smtp_dns_reply_filter, smtp_delivery_status_filter und ähnlich benannte Parameter für andere Postfix-Dämonen.
  • Verbesserte Konfigurationsdateisyntax mit Unterstützung für den ternären Operator wie ${name?{iftrue}:{iffalse}}, Vergleichsoperatoren wie $expr1_expr2}, pro-Milter- und pro-Policy-Server-Timeout und andere Einstellungen, master.cf-Parameter, die Whitespace enthalten, Import-/Export_Umgebungseinstellungen, die Whitespace enthalten, und „statische“ Tabellensuchergebnisse, die Whitespace enthalten.
  • Befehlsprofile pro Sitzung, die am Ende jeder eingehenden SMTP-Sitzung protokolliert werden. So wird beispielsweise ein Bot zum Raten von Passwörtern als „disconnect from name[addr] ehlo=1 auth=0/1 commands=1/2“ protokolliert, was bedeutet, dass der Client einen funktionierenden EHLO-Befehl, einen fehlgeschlagenen AUTH-Befehl und ein Auflegen ohne QUIT-Befehl gesendet hat.

Seit CentOS 6.0 wird als MTA Postfix installiert - aktuell ist dies der 2.10er Release. Im vorliegenden Konfigurationsbeispiel wollen wir uns aber im Detail mit der aktuellen Version V3 beschäftigen. Als Installationsquelle nutzen wie hierzu das Repository mailserver.guru.

Repository mailserver.guru

Damit nun bei der Installation und den späteren Updates nicht mehr den von CentOS 7 bereoitgestellen Postfix in der Version 2.10 sondern die aktuellere Version 3.x aus dem Repository mailserver.guru verwendet wird, passen wir die zugehörigen Konfigurationsdateien an. Als erstes exkludieren wir dei Postfix-Pakete aus dem CenbtOS-Base-Repository. Hierzu tragen wir die Option exclude=postfix* in der Datei /etc/yum.repos.d/CentOS-Base.repo nach.

 # vim /etc/yum.repos.d/CentOS-Base.repo
/etc/yum.repos.d/CentOS-Base.repo
# CentOS-LOCAL.repo
#
# This file uses a new mirrorlist system developed by Lance Davis for CentOS.
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the 
# remarked out baseurl= line instead.
#
# Version für den Zugriff auf das lokale Centos-Repository
 
[base-LC]
name=CentOS-7 - Base
baseurl=http://repository.nausch.org/centos/$releasever/os/$basearch/
priority=1
exclude=postfix*
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
 
#released updates 
[updates-LC]
name=CentOS-7 - Updates
baseurl=http://repository.nausch.org/centos/$releasever/updates/$basearch/
priority=1
exclude=postfix*
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
 
#additional packages that may be useful
[extras-LC]
name=CentOS-7 - Extras
baseurl=http://repository.nausch.org/centos/$releasever/extras/$basearch/
priority=1
gpgcheck=1
enabled = 1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
 
#additional packages that extend functionality of existing packages
[centosplus-LC]
name=CentOS-7 - Plus
baseurl=http://repository.nausch.org/centos/$releasever/centosplus/$basearch/
priority=2
exclude=postfix*
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

Als nächstes konfigurieren wir dann die Verwendung des Postfix 3.x-Relase aus dem Zweig testing des verwendeten Repositories mailserver.guru. Dazu passen wir die zugehörige Konfigurationsdatei wie folgt an:

 # vim /etc/yum.repos.d/mailserver.guru.repo
/etc/yum.repos.d/mailserver.guru.repo
[mailserver.guru-os]
name=Extra (Mailserver-)Packages for Enterprise Linux 7 -
baseurl=http://repo.mailserver.guru/7/os/$basearch
priority=5
enabled=1
# Django : 2019-01-26
# Postfix 3.x - Installation
exclude=postfix*
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/MAILSERVER.GURU-RPM-GPG-KEY-CentOS-7
 
 
[mailserver.guru-testing]
name=Testing (Mailserver-)Packages for Enterprise Linux 7 -
baseurl=http://repo.mailserver.guru/7/testing/$basearch/
priority=5
# Django : 2019-01-26
# Postfix 3.x - Installation
# default: enabled=0
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/MAILSERVER.GURU-RPM-GPG-KEY-CentOS-7

Postfix 3.x

Nun können wir den aktuellen Release von Postfix 3.x wie gewohnt mit Hilfe von yum einfach installieren.

 # yum install postfix -y

Was uns das RPM-Paket alles mitgebracht hat, erkunden wir bei Bedarf mit Hilfe des Befehls rpm -qil.

 # rpm -qil postfix
Name        : postfix
Epoch       : 2
Version     : 3.3.2
Release     : 1.el7
Architecture: x86_64
Install Date: Sat 26 Jan 2019 07:04:46 PM CET
Group       : System Environment/Daemons
Size        : 4217445
License     : IBM
Signature   : RSA/SHA1, Thu 17 Jan 2019 05:10:10 PM CET, Key ID 60ecfb9e8195aea0
Source RPM  : postfix-3.3.2-1.el7.src.rpm
Build Date  : Thu 17 Jan 2019 05:09:51 PM CET
Build Host  : vml000137.dmz.nausch.org
Relocations : (not relocatable)
Packager    : Django <django@mailserver.guru>
URL         : http://www.postfix.org
Summary     : Postfix Mail Transport Agent
Description :
Postfix is a Mail Transport Agent (MTA), supporting LDAP, SMTP AUTH (SASL),
TLS
/etc/pam.d/smtp
/etc/pam.d/smtp.postfix
/etc/postfix
/etc/postfix/access
/etc/postfix/canonical
/etc/postfix/dynamicmaps.cf
/etc/postfix/dynamicmaps.cf.d
/etc/postfix/generic
/etc/postfix/header_checks
/etc/postfix/main.cf
/etc/postfix/main.cf.proto
/etc/postfix/master.cf
/etc/postfix/master.cf.proto
/etc/postfix/postfix-files
/etc/postfix/relocated
/etc/postfix/transport
/etc/postfix/virtual
/etc/sasl2/smtpd.conf
/usr/bin/mailq
/usr/bin/mailq.postfix
/usr/bin/newaliases
/usr/bin/newaliases.postfix
/usr/bin/rmail
/usr/bin/rmail.postfix
/usr/lib/postfix/libpostfix-dns.so
/usr/lib/postfix/libpostfix-global.so
/usr/lib/postfix/libpostfix-master.so
/usr/lib/postfix/libpostfix-tls.so
/usr/lib/postfix/libpostfix-util.so
/usr/lib/sendmail
/usr/lib/sendmail.postfix
/usr/lib/systemd/system/postfix.service
/usr/libexec/postfix
/usr/libexec/postfix/aliasesdb
/usr/libexec/postfix/anvil
/usr/libexec/postfix/bounce
/usr/libexec/postfix/chroot-update
/usr/libexec/postfix/cleanup
/usr/libexec/postfix/discard
/usr/libexec/postfix/dnsblog
/usr/libexec/postfix/error
/usr/libexec/postfix/flush
/usr/libexec/postfix/lmtp
/usr/libexec/postfix/local
/usr/libexec/postfix/master
/usr/libexec/postfix/nqmgr
/usr/libexec/postfix/oqmgr
/usr/libexec/postfix/pickup
/usr/libexec/postfix/pipe
/usr/libexec/postfix/post-install
/usr/libexec/postfix/postfix-script
/usr/libexec/postfix/postfix-tls-script
/usr/libexec/postfix/postfix-wrapper
/usr/libexec/postfix/postmulti-script
/usr/libexec/postfix/postscreen
/usr/libexec/postfix/proxymap
/usr/libexec/postfix/qmgr
/usr/libexec/postfix/qmqpd
/usr/libexec/postfix/scache
/usr/libexec/postfix/showq
/usr/libexec/postfix/smtp
/usr/libexec/postfix/smtpd
/usr/libexec/postfix/spawn
/usr/libexec/postfix/tlsmgr
/usr/libexec/postfix/tlsproxy
/usr/libexec/postfix/trivial-rewrite
/usr/libexec/postfix/verify
/usr/libexec/postfix/virtual
/usr/sbin/postalias
/usr/sbin/postcat
/usr/sbin/postconf
/usr/sbin/postdrop
/usr/sbin/postfix
/usr/sbin/postkick
/usr/sbin/postlock
/usr/sbin/postlog
/usr/sbin/postmap
/usr/sbin/postmulti
/usr/sbin/postqueue
/usr/sbin/postsuper
/usr/sbin/sendmail
/usr/sbin/sendmail.postfix
/usr/sbin/smtp-sink
/usr/sbin/smtp-source
/usr/share/doc/postfix-3.3.2
/usr/share/doc/postfix-3.3.2/COMPATIBILITY
/usr/share/doc/postfix-3.3.2/LICENSE
/usr/share/doc/postfix-3.3.2/README-Postfix-SASL-RedHat.txt
/usr/share/doc/postfix-3.3.2/README_FILES
/usr/share/doc/postfix-3.3.2/README_FILES/AAAREADME
/usr/share/doc/postfix-3.3.2/README_FILES/ADDRESS_CLASS_README
/usr/share/doc/postfix-3.3.2/README_FILES/ADDRESS_REWRITING_README
/usr/share/doc/postfix-3.3.2/README_FILES/ADDRESS_VERIFICATION_README
/usr/share/doc/postfix-3.3.2/README_FILES/BACKSCATTER_README
/usr/share/doc/postfix-3.3.2/README_FILES/BASIC_CONFIGURATION_README
/usr/share/doc/postfix-3.3.2/README_FILES/BUILTIN_FILTER_README
/usr/share/doc/postfix-3.3.2/README_FILES/COMPATIBILITY_README
/usr/share/doc/postfix-3.3.2/README_FILES/CONNECTION_CACHE_README
/usr/share/doc/postfix-3.3.2/README_FILES/CONTENT_INSPECTION_README
/usr/share/doc/postfix-3.3.2/README_FILES/DATABASE_README
/usr/share/doc/postfix-3.3.2/README_FILES/DB_README
/usr/share/doc/postfix-3.3.2/README_FILES/DEBUG_README
/usr/share/doc/postfix-3.3.2/README_FILES/DSN_README
/usr/share/doc/postfix-3.3.2/README_FILES/ETRN_README
/usr/share/doc/postfix-3.3.2/README_FILES/FILTER_README
/usr/share/doc/postfix-3.3.2/README_FILES/FORWARD_SECRECY_README
/usr/share/doc/postfix-3.3.2/README_FILES/INSTALL
/usr/share/doc/postfix-3.3.2/README_FILES/IPV6_README
/usr/share/doc/postfix-3.3.2/README_FILES/LINUX_README
/usr/share/doc/postfix-3.3.2/README_FILES/LOCAL_RECIPIENT_README
/usr/share/doc/postfix-3.3.2/README_FILES/MAILDROP_README
/usr/share/doc/postfix-3.3.2/README_FILES/MEMCACHE_README
/usr/share/doc/postfix-3.3.2/README_FILES/MILTER_README
/usr/share/doc/postfix-3.3.2/README_FILES/MULTI_INSTANCE_README
/usr/share/doc/postfix-3.3.2/README_FILES/NFS_README
/usr/share/doc/postfix-3.3.2/README_FILES/OVERVIEW
/usr/share/doc/postfix-3.3.2/README_FILES/PACKAGE_README
/usr/share/doc/postfix-3.3.2/README_FILES/POSTSCREEN_README
/usr/share/doc/postfix-3.3.2/README_FILES/QSHAPE_README
/usr/share/doc/postfix-3.3.2/README_FILES/RELEASE_NOTES
/usr/share/doc/postfix-3.3.2/README_FILES/RESTRICTION_CLASS_README
/usr/share/doc/postfix-3.3.2/README_FILES/SASL_README
/usr/share/doc/postfix-3.3.2/README_FILES/SCHEDULER_README
/usr/share/doc/postfix-3.3.2/README_FILES/SMTPD_ACCESS_README
/usr/share/doc/postfix-3.3.2/README_FILES/SMTPD_POLICY_README
/usr/share/doc/postfix-3.3.2/README_FILES/SMTPD_PROXY_README
/usr/share/doc/postfix-3.3.2/README_FILES/SOHO_README
/usr/share/doc/postfix-3.3.2/README_FILES/STANDARD_CONFIGURATION_README
/usr/share/doc/postfix-3.3.2/README_FILES/STRESS_README
/usr/share/doc/postfix-3.3.2/README_FILES/TLS_LEGACY_README
/usr/share/doc/postfix-3.3.2/README_FILES/TLS_README
/usr/share/doc/postfix-3.3.2/README_FILES/TUNING_README
/usr/share/doc/postfix-3.3.2/README_FILES/ULTRIX_README
/usr/share/doc/postfix-3.3.2/README_FILES/UUCP_README
/usr/share/doc/postfix-3.3.2/README_FILES/VERP_README
/usr/share/doc/postfix-3.3.2/README_FILES/VIRTUAL_README
/usr/share/doc/postfix-3.3.2/README_FILES/XCLIENT_README
/usr/share/doc/postfix-3.3.2/README_FILES/XFORWARD_README
/usr/share/doc/postfix-3.3.2/TLS_ACKNOWLEDGEMENTS
/usr/share/doc/postfix-3.3.2/TLS_LICENSE
/usr/share/doc/postfix-3.3.2/bounce.cf.default
/usr/share/doc/postfix-3.3.2/examples
/usr/share/doc/postfix-3.3.2/examples/chroot-setup
/usr/share/doc/postfix-3.3.2/examples/chroot-setup/LINUX2
/usr/share/doc/postfix-3.3.2/examples/qmail-local
/usr/share/doc/postfix-3.3.2/examples/qmail-local/qmail-local.txt
/usr/share/doc/postfix-3.3.2/examples/smtpd-policy
/usr/share/doc/postfix-3.3.2/examples/smtpd-policy/README.SPF
/usr/share/doc/postfix-3.3.2/examples/smtpd-policy/greylist.pl
/usr/share/doc/postfix-3.3.2/main.cf.default
/usr/share/man/man1/mailq.1.gz
/usr/share/man/man1/mailq.postfix.1.gz
/usr/share/man/man1/newaliases.1.gz
/usr/share/man/man1/newaliases.postfix.1.gz
/usr/share/man/man1/postalias.1.gz
/usr/share/man/man1/postcat.1.gz
/usr/share/man/man1/postconf.1.gz
/usr/share/man/man1/postdrop.1.gz
/usr/share/man/man1/postfix-tls.1.gz
/usr/share/man/man1/postfix.1.gz
/usr/share/man/man1/postkick.1.gz
/usr/share/man/man1/postlock.1.gz
/usr/share/man/man1/postlog.1.gz
/usr/share/man/man1/postmap.1.gz
/usr/share/man/man1/postmulti.1.gz
/usr/share/man/man1/postqueue.1.gz
/usr/share/man/man1/postsuper.1.gz
/usr/share/man/man1/sendmail.postfix.1.gz
/usr/share/man/man1/smtp-sink.1.gz
/usr/share/man/man1/smtp-source.1.gz
/usr/share/man/man5/access.5.gz
/usr/share/man/man5/aliases.5.gz
/usr/share/man/man5/aliases.postfix.5.gz
/usr/share/man/man5/body_checks.5.gz
/usr/share/man/man5/bounce.5.gz
/usr/share/man/man5/canonical.5.gz
/usr/share/man/man5/cidr_table.5.gz
/usr/share/man/man5/generic.5.gz
/usr/share/man/man5/header_checks.5.gz
/usr/share/man/man5/master.5.gz
/usr/share/man/man5/memcache_table.5.gz
/usr/share/man/man5/nisplus_table.5.gz
/usr/share/man/man5/postconf.5.gz
/usr/share/man/man5/postfix-wrapper.5.gz
/usr/share/man/man5/regexp_table.5.gz
/usr/share/man/man5/relocated.5.gz
/usr/share/man/man5/socketmap_table.5.gz
/usr/share/man/man5/tcp_table.5.gz
/usr/share/man/man5/transport.5.gz
/usr/share/man/man5/virtual.5.gz
/usr/share/man/man8/anvil.8.gz
/usr/share/man/man8/bounce.8.gz
/usr/share/man/man8/cleanup.8.gz
/usr/share/man/man8/defer.8.gz
/usr/share/man/man8/discard.8.gz
/usr/share/man/man8/dnsblog.8.gz
/usr/share/man/man8/error.8.gz
/usr/share/man/man8/flush.8.gz
/usr/share/man/man8/lmtp.8.gz
/usr/share/man/man8/local.8.gz
/usr/share/man/man8/master.8.gz
/usr/share/man/man8/oqmgr.8.gz
/usr/share/man/man8/pickup.8.gz
/usr/share/man/man8/pipe.8.gz
/usr/share/man/man8/postscreen.8.gz
/usr/share/man/man8/proxymap.8.gz
/usr/share/man/man8/qmgr.8.gz
/usr/share/man/man8/qmqpd.8.gz
/usr/share/man/man8/scache.8.gz
/usr/share/man/man8/sendmail.8.gz
/usr/share/man/man8/showq.8.gz
/usr/share/man/man8/smtp.8.gz
/usr/share/man/man8/smtpd.8.gz
/usr/share/man/man8/spawn.8.gz
/usr/share/man/man8/tlsmgr.8.gz
/usr/share/man/man8/tlsproxy.8.gz
/usr/share/man/man8/trace.8.gz
/usr/share/man/man8/trivial-rewrite.8.gz
/usr/share/man/man8/verify.8.gz
/usr/share/man/man8/virtual.8.gz
/var/lib/misc/postfix.aliasesdb-stamp
/var/lib/postfix
/var/spool/postfix
/var/spool/postfix/active
/var/spool/postfix/bounce
/var/spool/postfix/corrupt
/var/spool/postfix/defer
/var/spool/postfix/deferred
/var/spool/postfix/flush
/var/spool/postfix/hold
/var/spool/postfix/incoming
/var/spool/postfix/maildrop
/var/spool/postfix/pid
/var/spool/postfix/private
/var/spool/postfix/public
/var/spool/postfix/saved
/var/spool/postfix/trace

Die Dokumentation zu unserem MTA finden wir wie gewohnt an Ort und Stelle im Verzeichnis /usr/share/doc/postfix-3.3.2 bzw. in den jeweils zugehörigen man-pages.

/usr/share/doc/postfix-3.3.2
├── bounce.cf.default
├── COMPATIBILITY
├── examples
│   ├── chroot-setup
│   │   └── LINUX2
│   ├── qmail-local
│   │   └── qmail-local.txt
│   └── smtpd-policy
│       ├── greylist.pl
│       └── README.SPF
├── LICENSE
├── main.cf.default
├── README_FILES
│   ├── AAAREADME
│   ├── ADDRESS_CLASS_README
│   ├── ADDRESS_REWRITING_README
│   ├── ADDRESS_VERIFICATION_README
│   ├── BACKSCATTER_README
│   ├── BASIC_CONFIGURATION_README
│   ├── BUILTIN_FILTER_README
│   ├── COMPATIBILITY_README
│   ├── CONNECTION_CACHE_README
│   ├── CONTENT_INSPECTION_README
│   ├── DATABASE_README
│   ├── DB_README
│   ├── DEBUG_README
│   ├── DSN_README
│   ├── ETRN_README
│   ├── FILTER_README
│   ├── FORWARD_SECRECY_README
│   ├── INSTALL
│   ├── IPV6_README
│   ├── LINUX_README
│   ├── LOCAL_RECIPIENT_README
│   ├── MAILDROP_README
│   ├── MEMCACHE_README
│   ├── MILTER_README
│   ├── MULTI_INSTANCE_README
│   ├── NFS_README
│   ├── OVERVIEW
│   ├── PACKAGE_README
│   ├── POSTSCREEN_README
│   ├── QSHAPE_README
│   ├── RELEASE_NOTES
│   ├── RESTRICTION_CLASS_README
│   ├── SASL_README
│   ├── SCHEDULER_README
│   ├── SMTPD_ACCESS_README
│   ├── SMTPD_POLICY_README
│   ├── SMTPD_PROXY_README
│   ├── SOHO_README
│   ├── STANDARD_CONFIGURATION_README
│   ├── STRESS_README
│   ├── TLS_LEGACY_README
│   ├── TLS_README
│   ├── TUNING_README
│   ├── ULTRIX_README
│   ├── UUCP_README
│   ├── VERP_README
│   ├── VIRTUAL_README
│   ├── XCLIENT_README
│   └── XFORWARD_README
├── README-Postfix-SASL-RedHat.txt
├── TLS_ACKNOWLEDGEMENTS
└── TLS_LICENSE

Wir tun also gutes daran uns diese Dokumente einzuverleiben bzw. bei Interesse heranzuziehen.

Der Großteil der Konfiguration von Postfix erfolgt über die beiden Hauptkonfigurationsdateien /etc/postfix/main.cf und /etc/postfix/master.cf. Im Konfigurationsverzeichnis /etc/postfix/ finden sich noch weitere Dateien die eine entscheidende Rolle spielen.

/etc/postfix/
├── access
├── canonical
├── dynamicmaps.cf
├── dynamicmaps.cf.d
├── generic
├── header_checks
├── main.cf
├── main.cf.proto
├── master.cf
├── master.cf.proto
├── postfix-files
├── relocated
├── transport
└── virtual

master.cf

Als erstes sehen wir uns die Hauptkonfigurationsdatei /etc/postfix/master.cf etwas genauer an.

Die Steuerung der in der Übersichtskizze von Postfix dargestellten Daemon und Module erfolgt mit Hilfe des master-Daemon und seiner Konfigurationsdatei master.cf, welches den Postfix-Main-Prozess definiert. Dieser Master-Prozess steuert und überwacht zum einen die einzelnen Postfix-Module, definiert wie viele Instanzen den einzelnen Modulen zugewiesen werden sollen. Zum anderen werden durch den Master-Prozess in regelmäßigen Abständen die Module zum Verwalten und Steuern der Queues gestartet.

Zur besseren Erklärung wurden die einzelnen Dienste und Befehle in der nachfolgenden Konfigurationsdatei mit Links zu den zugehörigen erklärenden Abschnitte der Wikiseite Postfix, der sichere Mailserver (MTA) unter CentOS 7.x versehen!

 # vim /etc/postfix/master.cf
/etc/postfix/master.cf
#
# Postfix master process configuration file.  For details on the format
# of the file, see the master(5) manual page (command: "man 5 master" or
# on-line: http://www.postfix.org/master.5.html).
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type  private unpriv  chroot  wakeup  maxproc command + args
#               (yes)   (yes)   (no)    (never) (100)
# ==========================================================================
smtp      inet  n       -       n       -       -       smtpd
#smtp      inet  n       -       n       -       1       postscreen
#smtpd     pass  -       -       n       -       -       smtpd
#dnsblog   unix  -       -       n       -       0       dnsblog
#tlsproxy  unix  -       -       n       -       0       tlsproxy
#submission inet n       -       n       -       -       smtpd
#  -o syslog_name=postfix/submission
#  -o smtpd_tls_security_level=encrypt
#  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_tls_auth_only=yes
#  -o smtpd_reject_unlisted_recipient=no
#  -o smtpd_client_restrictions=$mua_client_restrictions
#  -o smtpd_helo_restrictions=$mua_helo_restrictions
#  -o smtpd_sender_restrictions=$mua_sender_restrictions
#  -o smtpd_recipient_restrictions=
#  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING
#smtps     inet  n       -       n       -       -       smtpd
#  -o syslog_name=postfix/smtps
#  -o smtpd_tls_wrappermode=yes
#  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_reject_unlisted_recipient=no
#  -o smtpd_client_restrictions=$mua_client_restrictions
#  -o smtpd_helo_restrictions=$mua_helo_restrictions
#  -o smtpd_sender_restrictions=$mua_sender_restrictions
#  -o smtpd_recipient_restrictions=
#  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING
#628       inet  n       -       n       -       -       qmqpd
pickup    unix  n       -       n       60      1       pickup
cleanup   unix  n       -       n       -       0       cleanup
qmgr      unix  n       -       n       300     1       qmgr
#qmgr     unix  n       -       n       300     1       oqmgr
tlsmgr    unix  -       -       n       1000?   1       tlsmgr
rewrite   unix  -       -       n       -       -       trivial-rewrite
bounce    unix  -       -       n       -       0       bounce
defer     unix  -       -       n       -       0       bounce
trace     unix  -       -       n       -       0       bounce
verify    unix  -       -       n       -       1       verify
flush     unix  n       -       n       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       n       -       -       smtp
relay     unix  -       -       n       -       -       smtp
        -o syslog_name=postfix/$service_name
#       -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq     unix  n       -       n       -       -       showq
error     unix  -       -       n       -       -       error
retry     unix  -       -       n       -       -       error
discard   unix  -       -       n       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       n       -       -       lmtp
anvil     unix  -       -       n       -       1       anvil
scache    unix  -       -       n       -       1       scache
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent.  See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
#maildrop  unix  -       n       n       -       -       pipe
#  flags=DRhu user=vmail argv=/usr/local/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# Recent Cyrus versions can use the existing "lmtp" master.cf entry.
#
# Specify in cyrus.conf:
#   lmtp    cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4
#
# Specify in main.cf one or more of the following:
#  mailbox_transport = lmtp:inet:localhost
#  virtual_transport = lmtp:inet:localhost
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus     unix  -       n       n       -       -       pipe
#  user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -r ${sender} -m ${extension} ${user}
#
# ====================================================================
#
# Old example of delivery via Cyrus.
#
#old-cyrus unix  -       n       n       -       -       pipe
#  flags=R user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# See the Postfix UUCP_README file for configuration details.
#
#uucp      unix  -       n       n       -       -       pipe
#  flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# ====================================================================
#
# Other external delivery methods.
#
#ifmail    unix  -       n       n       -       -       pipe
#  flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
#
#bsmtp     unix  -       n       n       -       -       pipe
#  flags=Fq. user=bsmtp argv=/usr/local/sbin/bsmtp -f $sender $nexthop $recipient
#
#scalemail-backend unix -       n       n       -       2       pipe
#  flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store
#  ${nexthop} ${user} ${extension}
#
#mailman   unix  -       n       n       -       -       pipe
#  flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
#  ${nexthop} ${user}

main.cf

Die eigentliche Konfiguration unseres Postfix MTAs erfolgt mit Hilfe der Hauptkonfigurationsdatei main.cf. Diese Konfigurationsdatei ist durch die vielen sehr guten Dokumentationshinweise doch sehr angewachsen, aber im Grunde beschränkt sich diese auf ein paar wenige „aktive“ Zeilen.

In der Standardkonfiguration sind alle wichtigen Parameter bereits mit einem Default-Wert vorbelegt.

So hat Postfix 2.10 816 Defaultparameter.

 # postconf -d | grep mail_version
 mail_version = 2.10.1
 milter_macro_v = $mail_name $mail_version
 # postconf -d | wc -l
 816

Postfix 2.11 bringt uns 832 Defaultparameter mit.

 # postconf -d | grep mail_version
 mail_version = 2.11.6
 milter_macro_v = $mail_name $mail_version
 # postconf -d | wc -l
 847

Bei der neuen aktuellen Version 3.x von Postfix erhöhte sich bedingt durch die zusätzlichen Features abermals die Anzahl der Defaultparameter auf 885.

 # postconf -d | grep mail_version
 mail_version = 3.3.2
 milter_macro_v = $mail_name $mail_version
 # postconf -d | wc -l
 895

Werfen wir einfach einen Blick in diese Hauptkonfigurationmsdatei /etc/postfix/main.cf.

 # less /etc/postfix/main.cf
/etc/postfix/main.cf
# Global Postfix configuration file. This file lists only a subset
# of all parameters. For the syntax, and for a complete parameter
# list, see the postconf(5) manual page (command: "man 5 postconf").
#
# For common configuration examples, see BASIC_CONFIGURATION_README
# and STANDARD_CONFIGURATION_README. To find these documents, use
# the command "postconf html_directory readme_directory", or go to
# http://www.postfix.org/BASIC_CONFIGURATION_README.html etc.
#
# For best results, change no more than 2-3 parameters at a time,
# and test if Postfix still works after every change.
 
# COMPATIBILITY
#
# The compatibility_level determines what default settings Postfix
# will use for main.cf and master.cf settings. These defaults will
# change over time.
#
# To avoid breaking things, Postfix will use backwards-compatible
# default settings and log where it uses those old backwards-compatible
# default settings, until the system administrator has determined
# if any backwards-compatible default settings need to be made
# permanent in main.cf or master.cf.
#
# When this review is complete, update the compatibility_level setting
# below as recommended in the RELEASE_NOTES file.
#
# The level below is what should be used with new (not upgrade) installs.
#
compatibility_level = 2
 
# SOFT BOUNCE
#
# The soft_bounce parameter provides a limited safety net for
# testing.  When soft_bounce is enabled, mail will remain queued that
# would otherwise bounce. This parameter disables locally-generated
# bounces, and prevents the SMTP server from rejecting mail permanently
# (by changing 5xx replies into 4xx replies). However, soft_bounce
# is no cure for address rewriting mistakes or mail routing mistakes.
#
#soft_bounce = no
 
# LOCAL PATHNAME INFORMATION
#
# The queue_directory specifies the location of the Postfix queue.
# This is also the root directory of Postfix daemons that run chrooted.
# See the files in examples/chroot-setup for setting up Postfix chroot
# environments on different UNIX systems.
#
queue_directory = /var/spool/postfix
 
# The command_directory parameter specifies the location of all
# postXXX commands.
#
command_directory = /usr/sbin
 
# The daemon_directory parameter specifies the location of all Postfix
# daemon programs (i.e. programs listed in the master.cf file). This
# directory must be owned by root.
#
daemon_directory = /usr/libexec/postfix
 
# The data_directory parameter specifies the location of Postfix-writable
# data files (caches, random numbers). This directory must be owned
# by the mail_owner account (see below).
#
data_directory = /var/lib/postfix
 
# QUEUE AND PROCESS OWNERSHIP
#
# The mail_owner parameter specifies the owner of the Postfix queue
# and of most Postfix daemon processes.  Specify the name of a user
# account THAT DOES NOT SHARE ITS USER OR GROUP ID WITH OTHER ACCOUNTS
# AND THAT OWNS NO OTHER FILES OR PROCESSES ON THE SYSTEM.  In
# particular, don't specify nobody or daemon. PLEASE USE A DEDICATED
# USER.
#
mail_owner = postfix
 
# The default_privs parameter specifies the default rights used by
# the local delivery agent for delivery to external file or command.
# These rights are used in the absence of a recipient user context.
# DO NOT SPECIFY A PRIVILEGED USER OR THE POSTFIX OWNER.
#
#default_privs = nobody
 
# INTERNET HOST AND DOMAIN NAMES
# 
# The myhostname parameter specifies the internet hostname of this
# mail system. The default is to use the fully-qualified domain name
# from gethostname(). $myhostname is used as a default value for many
# other configuration parameters.
#
#myhostname = host.domain.tld
#myhostname = virtual.domain.tld
 
# The mydomain parameter specifies the local internet domain name.
# The default is to use $myhostname minus the first component.
# $mydomain is used as a default value for many other configuration
# parameters.
#
#mydomain = domain.tld
 
# SENDING MAIL
# 
# The myorigin parameter specifies the domain that locally-posted
# mail appears to come from. The default is to append $myhostname,
# which is fine for small sites.  If you run a domain with multiple
# machines, you should (1) change this to $mydomain and (2) set up
# a domain-wide alias database that aliases each user to
# user@that.users.mailhost.
#
# For the sake of consistency between sender and recipient addresses,
# myorigin also specifies the default domain name that is appended
# to recipient addresses that have no @domain part.
#
#myorigin = $myhostname
#myorigin = $mydomain
 
# RECEIVING MAIL
 
# The inet_interfaces parameter specifies the network interface
# addresses that this mail system receives mail on.  By default,
# the software claims all active interfaces on the machine. The
# parameter also controls delivery of mail to user@[ip.address].
#
# See also the proxy_interfaces parameter, for network addresses that
# are forwarded to us via a proxy or network address translator.
#
# Note: you need to stop/start Postfix when this parameter changes.
#
#inet_interfaces = all
#inet_interfaces = $myhostname
#inet_interfaces = $myhostname, localhost
inet_interfaces = localhost
 
# Enable IPv4, and IPv6 if supported
#inet_protocols = ipv4
 
# The proxy_interfaces parameter specifies the network interface
# addresses that this mail system receives mail on by way of a
# proxy or network address translation unit. This setting extends
# the address list specified with the inet_interfaces parameter.
#
# You must specify your proxy/NAT addresses when your system is a
# backup MX host for other domains, otherwise mail delivery loops
# will happen when the primary MX host is down.
#
#proxy_interfaces =
#proxy_interfaces = 1.2.3.4
 
# The mydestination parameter specifies the list of domains that this
# machine considers itself the final destination for.
#
# These domains are routed to the delivery agent specified with the
# local_transport parameter setting. By default, that is the UNIX
# compatible delivery agent that lookups all recipients in /etc/passwd
# and /etc/aliases or their equivalent.
#
# The default is $myhostname + localhost.$mydomain + localhost.  On
# a mail domain gateway, you should also include $mydomain.
#
# Do not specify the names of virtual domains - those domains are
# specified elsewhere (see VIRTUAL_README).
#
# Do not specify the names of domains that this machine is backup MX
# host for. Specify those names via the relay_domains settings for
# the SMTP server, or use permit_mx_backup if you are lazy (see
# STANDARD_CONFIGURATION_README).
#
# The local machine is always the final destination for mail addressed
# to user@[the.net.work.address] of an interface that the mail system
# receives mail on (see the inet_interfaces parameter).
#
# Specify a list of host or domain names, /file/name or type:table
# patterns, separated by commas and/or whitespace. A /file/name
# pattern is replaced by its contents; a type:table is matched when
# a name matches a lookup key (the right-hand side is ignored).
# Continue long lines by starting the next line with whitespace.
#
# See also below, section "REJECTING MAIL FOR UNKNOWN LOCAL USERS".
#
mydestination = $myhostname, localhost.$mydomain, localhost
#mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
#mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain,
#	mail.$mydomain, www.$mydomain, ftp.$mydomain
 
# REJECTING MAIL FOR UNKNOWN LOCAL USERS
#
# The local_recipient_maps parameter specifies optional lookup tables
# with all names or addresses of users that are local with respect
# to $mydestination, $inet_interfaces or $proxy_interfaces.
#
# If this parameter is defined, then the SMTP server will reject
# mail for unknown local users. This parameter is defined by default.
#
# To turn off local recipient checking in the SMTP server, specify
# local_recipient_maps = (i.e. empty).
#
# The default setting assumes that you use the default Postfix local
# delivery agent for local delivery. You need to update the
# local_recipient_maps setting if:
#
# - You define $mydestination domain recipients in files other than
#   /etc/passwd, /etc/aliases, or the $virtual_alias_maps files.
#   For example, you define $mydestination domain recipients in    
#   the $virtual_mailbox_maps files.
#
# - You redefine the local delivery agent in master.cf.
#
# - You redefine the "local_transport" setting in main.cf.
#
# - You use the "luser_relay", "mailbox_transport", or "fallback_transport"
#   feature of the Postfix local delivery agent (see local(8)).
#
# Details are described in the LOCAL_RECIPIENT_README file.
#
# Beware: if the Postfix SMTP server runs chrooted, you probably have
# to access the passwd file via the proxymap service, in order to
# overcome chroot restrictions. The alternative, having a copy of
# the system passwd file in the chroot jail is just not practical.
#
# The right-hand side of the lookup tables is conveniently ignored.
# In the left-hand side, specify a bare username, an @domain.tld
# wild-card, or specify a user@domain.tld address.
# 
#local_recipient_maps = unix:passwd.byname $alias_maps
#local_recipient_maps = proxy:unix:passwd.byname $alias_maps
#local_recipient_maps =
 
# The unknown_local_recipient_reject_code specifies the SMTP server
# response code when a recipient domain matches $mydestination or
# ${proxy,inet}_interfaces, while $local_recipient_maps is non-empty
# and the recipient address or address local-part is not found.
#
# The default setting is 550 (reject mail) but it is safer to start
# with 450 (try again later) until you are certain that your
# local_recipient_maps settings are OK.
#
unknown_local_recipient_reject_code = 550
 
# TRUST AND RELAY CONTROL
 
# The mynetworks parameter specifies the list of "trusted" SMTP
# clients that have more privileges than "strangers".
#
# In particular, "trusted" SMTP clients are allowed to relay mail
# through Postfix.  See the smtpd_recipient_restrictions parameter
# in postconf(5).
#
# You can specify the list of "trusted" network addresses by hand
# or you can let Postfix do it for you (which is the default).
#
# By default (mynetworks_style = subnet), Postfix "trusts" SMTP
# clients in the same IP subnetworks as the local machine.
# On Linux, this does works correctly only with interfaces specified
# with the "ifconfig" command.
# 
# Specify "mynetworks_style = class" when Postfix should "trust" SMTP
# clients in the same IP class A/B/C networks as the local machine.
# Don't do this with a dialup site - it would cause Postfix to "trust"
# your entire provider's network.  Instead, specify an explicit
# mynetworks list by hand, as described below.
#  
# Specify "mynetworks_style = host" when Postfix should "trust"
# only the local machine.
# 
#mynetworks_style = class
#mynetworks_style = subnet
#mynetworks_style = host
 
# Alternatively, you can specify the mynetworks list by hand, in
# which case Postfix ignores the mynetworks_style setting.
#
# Specify an explicit list of network/netmask patterns, where the
# mask specifies the number of bits in the network part of a host
# address.
#
# You can also specify the absolute pathname of a pattern file instead
# of listing the patterns here. Specify type:table for table-based lookups
# (the value on the table right-hand side is not used).
#
#mynetworks = 168.100.189.0/28, 127.0.0.0/8
#mynetworks = $config_directory/mynetworks
#mynetworks = hash:/etc/postfix/network_table
 
# The relay_domains parameter restricts what destinations this system will
# relay mail to.  See the smtpd_recipient_restrictions description in
# postconf(5) for detailed information.
#
# By default, Postfix relays mail
# - from "trusted" clients (IP address matches $mynetworks) to any destination,
# - from "untrusted" clients to destinations that match $relay_domains or
#   subdomains thereof, except addresses with sender-specified routing.
# The default relay_domains value is $mydestination.
# 
# In addition to the above, the Postfix SMTP server by default accepts mail
# that Postfix is final destination for:
# - destinations that match $inet_interfaces or $proxy_interfaces,
# - destinations that match $mydestination
# - destinations that match $virtual_alias_domains,
# - destinations that match $virtual_mailbox_domains.
# These destinations do not need to be listed in $relay_domains.
# 
# Specify a list of hosts or domains, /file/name patterns or type:name
# lookup tables, separated by commas and/or whitespace.  Continue
# long lines by starting the next line with whitespace. A file name
# is replaced by its contents; a type:name table is matched when a
# (parent) domain appears as lookup key.
#
# NOTE: Postfix will not automatically forward mail for domains that
# list this system as their primary or backup MX host. See the
# permit_mx_backup restriction description in postconf(5).
#
#relay_domains = $mydestination
 
# INTERNET OR INTRANET
 
# The relayhost parameter specifies the default host to send mail to
# when no entry is matched in the optional transport(5) table. When
# no relayhost is given, mail is routed directly to the destination.
#
# On an intranet, specify the organizational domain name. If your
# internal DNS uses no MX records, specify the name of the intranet
# gateway host instead.
#
# In the case of SMTP, specify a domain, host, host:port, [host]:port,
# [address] or [address]:port; the form [host] turns off MX lookups.
#
# If you're connected via UUCP, see also the default_transport parameter.
#
#relayhost = $mydomain
#relayhost = [gateway.my.domain]
#relayhost = [mailserver.isp.tld]
#relayhost = uucphost
#relayhost = [an.ip.add.ress]
 
# REJECTING UNKNOWN RELAY USERS
#
# The relay_recipient_maps parameter specifies optional lookup tables
# with all addresses in the domains that match $relay_domains.
#
# If this parameter is defined, then the SMTP server will reject
# mail for unknown relay users. This feature is off by default.
#
# The right-hand side of the lookup tables is conveniently ignored.
# In the left-hand side, specify an @domain.tld wild-card, or specify
# a user@domain.tld address.
# 
#relay_recipient_maps = hash:/etc/postfix/relay_recipients
 
# INPUT RATE CONTROL
#
# The in_flow_delay configuration parameter implements mail input
# flow control. This feature is turned on by default, although it
# still needs further development (it's disabled on SCO UNIX due
# to an SCO bug).
# 
# A Postfix process will pause for $in_flow_delay seconds before
# accepting a new message, when the message arrival rate exceeds the
# message delivery rate. With the default 100 SMTP server process
# limit, this limits the mail inflow to 100 messages a second more
# than the number of messages delivered per second.
# 
# Specify 0 to disable the feature. Valid delays are 0..10.
# 
#in_flow_delay = 1s
 
# ADDRESS REWRITING
#
# The ADDRESS_REWRITING_README document gives information about
# address masquerading or other forms of address rewriting including
# username->Firstname.Lastname mapping.
 
# ADDRESS REDIRECTION (VIRTUAL DOMAIN)
#
# The VIRTUAL_README document gives information about the many forms
# of domain hosting that Postfix supports.
 
# "USER HAS MOVED" BOUNCE MESSAGES
#
# See the discussion in the ADDRESS_REWRITING_README document.
 
# TRANSPORT MAP
#
# See the discussion in the ADDRESS_REWRITING_README document.
 
# ALIAS DATABASE
#
# The alias_maps parameter specifies the list of alias databases used
# by the local delivery agent. The default list is system dependent.
#
# On systems with NIS, the default is to search the local alias
# database, then the NIS alias database. See aliases(5) for syntax
# details.
# 
# If you change the alias database, run "postalias /etc/aliases" (or
# wherever your system stores the mail alias file), or simply run
# "newaliases" to build the necessary DBM or DB file.
#
# It will take a minute or so before changes become visible.  Use
# "postfix reload" to eliminate the delay.
#
#alias_maps = dbm:/etc/aliases
alias_maps = hash:/etc/aliases
#alias_maps = hash:/etc/aliases, nis:mail.aliases
#alias_maps = netinfo:/aliases
 
# The alias_database parameter specifies the alias database(s) that
# are built with "newaliases" or "sendmail -bi".  This is a separate
# configuration parameter, because alias_maps (see above) may specify
# tables that are not necessarily all under control by Postfix.
#
#alias_database = dbm:/etc/aliases
#alias_database = dbm:/etc/mail/aliases
alias_database = hash:/etc/aliases
#alias_database = hash:/etc/aliases, hash:/opt/majordomo/aliases
 
# ADDRESS EXTENSIONS (e.g., user+foo)
#
# The recipient_delimiter parameter specifies the separator between
# user names and address extensions (user+foo). See canonical(5),
# local(8), relocated(5) and virtual(5) for the effects this has on
# aliases, canonical, virtual, relocated and .forward file lookups.
# Basically, the software tries user+foo and .forward+foo before
# trying user and .forward.
#
#recipient_delimiter = +
 
# DELIVERY TO MAILBOX
#
# The home_mailbox parameter specifies the optional pathname of a
# mailbox file relative to a user's home directory. The default
# mailbox file is /var/spool/mail/user or /var/mail/user.  Specify
# "Maildir/" for qmail-style delivery (the / is required).
#
#home_mailbox = Mailbox
#home_mailbox = Maildir/
 
# The mail_spool_directory parameter specifies the directory where
# UNIX-style mailboxes are kept. The default setting depends on the
# system type.
#
#mail_spool_directory = /var/mail
#mail_spool_directory = /var/spool/mail
 
# The mailbox_command parameter specifies the optional external
# command to use instead of mailbox delivery. The command is run as
# the recipient with proper HOME, SHELL and LOGNAME environment settings.
# Exception:  delivery for root is done as $default_user.
#
# Other environment variables of interest: USER (recipient username),
# EXTENSION (address extension), DOMAIN (domain part of address),
# and LOCAL (the address localpart).
#
# Unlike other Postfix configuration parameters, the mailbox_command
# parameter is not subjected to $parameter substitutions. This is to
# make it easier to specify shell syntax (see example below).
#
# Avoid shell meta characters because they will force Postfix to run
# an expensive shell process. Procmail alone is expensive enough.
#
# IF YOU USE THIS TO DELIVER MAIL SYSTEM-WIDE, YOU MUST SET UP AN
# ALIAS THAT FORWARDS MAIL FOR ROOT TO A REAL USER.
#
#mailbox_command = /some/where/procmail
#mailbox_command = /some/where/procmail -a "$EXTENSION"
 
# The mailbox_transport specifies the optional transport in master.cf
# to use after processing aliases and .forward files. This parameter
# has precedence over the mailbox_command, fallback_transport and
# luser_relay parameters.
#
# Specify a string of the form transport:nexthop, where transport is
# the name of a mail delivery transport defined in master.cf.  The
# :nexthop part is optional. For more details see the sample transport
# configuration file.
#
# NOTE: if you use this feature for accounts not in the UNIX password
# file, then you must update the "local_recipient_maps" setting in
# the main.cf file, otherwise the SMTP server will reject mail for    
# non-UNIX accounts with "User unknown in local recipient table".
#
# Cyrus IMAP over LMTP. Specify ``lmtpunix      cmd="lmtpd"
# listen="/var/imap/socket/lmtp" prefork=0'' in cyrus.conf.
#mailbox_transport = lmtp:unix:/var/lib/imap/socket/lmtp
 
# If using the cyrus-imapd IMAP server deliver local mail to the IMAP
# server using LMTP (Local Mail Transport Protocol), this is prefered
# over the older cyrus deliver program by setting the
# mailbox_transport as below:
#
# mailbox_transport = lmtp:unix:/var/lib/imap/socket/lmtp
#
# The efficiency of LMTP delivery for cyrus-imapd can be enhanced via
# these settings.
#
# local_destination_recipient_limit = 300
# local_destination_concurrency_limit = 5
#
# Of course you should adjust these settings as appropriate for the
# capacity of the hardware you are using. The recipient limit setting
# can be used to take advantage of the single instance message store
# capability of Cyrus. The concurrency limit can be used to control
# how many simultaneous LMTP sessions will be permitted to the Cyrus
# message store. 
#
# Cyrus IMAP via command line. Uncomment the "cyrus...pipe" and
# subsequent line in master.cf.
#mailbox_transport = cyrus
 
# The fallback_transport specifies the optional transport in master.cf
# to use for recipients that are not found in the UNIX passwd database.
# This parameter has precedence over the luser_relay parameter.
#
# Specify a string of the form transport:nexthop, where transport is
# the name of a mail delivery transport defined in master.cf.  The
# :nexthop part is optional. For more details see the sample transport
# configuration file.
#
# NOTE: if you use this feature for accounts not in the UNIX password
# file, then you must update the "local_recipient_maps" setting in
# the main.cf file, otherwise the SMTP server will reject mail for    
# non-UNIX accounts with "User unknown in local recipient table".
#
#fallback_transport = lmtp:unix:/var/lib/imap/socket/lmtp
#fallback_transport =
 
# The luser_relay parameter specifies an optional destination address
# for unknown recipients.  By default, mail for unknown@$mydestination,
# unknown@[$inet_interfaces] or unknown@[$proxy_interfaces] is returned
# as undeliverable.
#
# The following expansions are done on luser_relay: $user (recipient
# username), $shell (recipient shell), $home (recipient home directory),
# $recipient (full recipient address), $extension (recipient address
# extension), $domain (recipient domain), $local (entire recipient
# localpart), $recipient_delimiter. Specify ${name?value} or
# ${name:value} to expand value only when $name does (does not) exist.
#
# luser_relay works only for the default Postfix local delivery agent.
#
# NOTE: if you use this feature for accounts not in the UNIX password
# file, then you must specify "local_recipient_maps =" (i.e. empty) in
# the main.cf file, otherwise the SMTP server will reject mail for    
# non-UNIX accounts with "User unknown in local recipient table".
#
#luser_relay = $user@other.host
#luser_relay = $local@other.host
#luser_relay = admin+$local
 
# JUNK MAIL CONTROLS
# 
# The controls listed here are only a very small subset. The file
# SMTPD_ACCESS_README provides an overview.
 
# The header_checks parameter specifies an optional table with patterns
# that each logical message header is matched against, including
# headers that span multiple physical lines.
#
# By default, these patterns also apply to MIME headers and to the
# headers of attached messages. With older Postfix versions, MIME and
# attached message headers were treated as body text.
#
# For details, see "man header_checks".
#
#header_checks = regexp:/etc/postfix/header_checks
 
# FAST ETRN SERVICE
#
# Postfix maintains per-destination logfiles with information about
# deferred mail, so that mail can be flushed quickly with the SMTP
# "ETRN domain.tld" command, or by executing "sendmail -qRdomain.tld".
# See the ETRN_README document for a detailed description.
# 
# The fast_flush_domains parameter controls what destinations are
# eligible for this service. By default, they are all domains that
# this server is willing to relay mail to.
# 
#fast_flush_domains = $relay_domains
 
# SHOW SOFTWARE VERSION OR NOT
#
# The smtpd_banner parameter specifies the text that follows the 220
# code in the SMTP server's greeting banner. Some people like to see
# the mail version advertised. By default, Postfix shows no version.
#
# You MUST specify $myhostname at the start of the text. That is an
# RFC requirement. Postfix itself does not care.
#
#smtpd_banner = $myhostname ESMTP $mail_name
#smtpd_banner = $myhostname ESMTP $mail_name ($mail_version)
 
# PARALLEL DELIVERY TO THE SAME DESTINATION
#
# How many parallel deliveries to the same user or domain? With local
# delivery, it does not make sense to do massively parallel delivery
# to the same user, because mailbox updates must happen sequentially,
# and expensive pipelines in .forward files can cause disasters when
# too many are run at the same time. With SMTP deliveries, 10
# simultaneous connections to the same domain could be sufficient to
# raise eyebrows.
# 
# Each message delivery transport has its XXX_destination_concurrency_limit
# parameter.  The default is $default_destination_concurrency_limit for
# most delivery transports. For the local delivery agent the default is 2.
 
#local_destination_concurrency_limit = 2
#default_destination_concurrency_limit = 20
 
# DEBUGGING CONTROL
#
# The debug_peer_level parameter specifies the increment in verbose
# logging level when an SMTP client or server host name or address
# matches a pattern in the debug_peer_list parameter.
#
debug_peer_level = 2
 
# The debug_peer_list parameter specifies an optional list of domain
# or network patterns, /file/name patterns or type:name tables. When
# an SMTP client or server host name or address matches a pattern,
# increase the verbose logging level by the amount specified in the
# debug_peer_level parameter.
#
#debug_peer_list = 127.0.0.1
#debug_peer_list = some.domain
 
# The debugger_command specifies the external command that is executed
# when a Postfix daemon program is run with the -D option.
#
# Use "command .. & sleep 5" so that the debugger can attach before
# the process marches on. If you use an X-based debugger, be sure to
# set up your XAUTHORITY environment variable before starting Postfix.
#
debugger_command =
	 PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
	 ddd $daemon_directory/$process_name $process_id & sleep 5
 
# If you can't use X, use this to capture the call stack when a
# daemon crashes. The result is in a file in the configuration
# directory, and is named after the process name and the process ID.
#
# debugger_command =
#	PATH=/bin:/usr/bin:/usr/local/bin; export PATH; (echo cont;
#	echo where) | gdb $daemon_directory/$process_name $process_id 2>&1
#	>$config_directory/$process_name.$process_id.log & sleep 5
#
# Another possibility is to run gdb under a detached screen session.
# To attach to the screen session, su root and run "screen -r
# <id_string>" where <id_string> uniquely matches one of the detached
# sessions (from "screen -list").
#
# debugger_command =
#	PATH=/bin:/usr/bin:/sbin:/usr/sbin; export PATH; screen
#	-dmS $process_name gdb $daemon_directory/$process_name
#	$process_id & sleep 1
 
# INSTALL-TIME CONFIGURATION INFORMATION
#
# The following parameters are used when installing a new Postfix version.
# 
# sendmail_path: The full pathname of the Postfix sendmail command.
# This is the Sendmail-compatible mail posting interface.
# 
sendmail_path = /usr/sbin/sendmail.postfix
 
# newaliases_path: The full pathname of the Postfix newaliases command.
# This is the Sendmail-compatible command to build alias databases.
#
newaliases_path = /usr/bin/newaliases.postfix
 
# mailq_path: The full pathname of the Postfix mailq command.  This
# is the Sendmail-compatible mail queue listing command.
# 
mailq_path = /usr/bin/mailq.postfix
 
# setgid_group: The group for mail submission and queue management
# commands.  This must be a group name with a numerical group ID that
# is not shared with other accounts, not even with the Postfix account.
#
setgid_group = postdrop
 
# html_directory: The location of the Postfix HTML documentation.
#
html_directory = no
 
# manpage_directory: The location of the Postfix on-line manual pages.
#
manpage_directory = /usr/share/man
 
# sample_directory: The location of the Postfix sample configuration files.
# This parameter is obsolete as of Postfix 2.1.
#
sample_directory = /usr/share/doc/postfix-3.3.2/samples
 
# readme_directory: The location of the Postfix README files.
#
readme_directory = /usr/share/doc/postfix-3.3.2/README_FILES
meta_directory = /etc/postfix
shlib_directory = /usr/lib/postfix

Mit Hilfe des Programms postconf können wir während des laufenden Betriebes einzelnen Parameter, abfragen und auch ändern. Wollen wir uns alle Definitionen ansehen, die von den Standardvorgaben abweichen, verwenden wir den folgenden Aufruf:

# postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
command_directory = /usr/sbin
compatibility_level = 2
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin ddd $daemon_directory/$process_name $process_id & sleep 5
html_directory = no
inet_interfaces = localhost
mail_owner = postfix
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
meta_directory = /etc/postfix
mydestination = $myhostname, localhost.$mydomain, localhost
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-3.3.2/README_FILES
sample_directory = /usr/share/doc/postfix-3.3.2/samples
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
shlib_directory = /usr/lib/postfix
unknown_local_recipient_reject_code = 550

Wollen wir uns alle Standard-Definitionen ansehen verwenden wir den folgenden Aufruf:

 # postconf -d
2bounce_notice_recipient = postmaster
access_map_defer_code = 450
access_map_reject_code = 554
address_verify_cache_cleanup_interval = 12h
address_verify_default_transport = $default_transport
address_verify_local_transport = $local_transport
address_verify_map = btree:$data_directory/verify_cache
address_verify_negative_cache = yes
address_verify_negative_expire_time = 3d
address_verify_negative_refresh_time = 3h
address_verify_pending_request_limit = 5000
address_verify_poll_count = ${stress?{1}:{3}}
address_verify_poll_delay = 3s
address_verify_positive_expire_time = 31d
address_verify_positive_refresh_time = 7d
address_verify_relay_transport = $relay_transport
address_verify_relayhost = $relayhost
address_verify_sender = $double_bounce_sender
address_verify_sender_dependent_default_transport_maps = $sender_dependent_default_transport_maps
address_verify_sender_dependent_relayhost_maps = $sender_dependent_relayhost_maps
address_verify_sender_ttl = 0s
address_verify_service_name = verify
address_verify_transport_maps = $transport_maps
address_verify_virtual_transport = $virtual_transport
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases, nis:mail.aliases
allow_mail_to_commands = alias, forward
allow_mail_to_files = alias, forward
allow_min_user = no
allow_percent_hack = yes
allow_untrusted_routing = no
alternate_config_directories =
always_add_missing_headers = no
always_bcc =
anvil_rate_time_unit = 60s
anvil_status_update_time = 600s
append_at_myorigin = yes
append_dot_mydomain = ${{$compatibility_level} < {1} ? {yes} : {no}}
application_event_drain_time = 100s
authorized_flush_users = static:anyone
authorized_mailq_users = static:anyone
authorized_submit_users = static:anyone
backwards_bounce_logfile_compatibility = yes
berkeley_db_create_buffer_size = 16777216
berkeley_db_read_buffer_size = 131072
best_mx_transport =
biff = yes
body_checks =
body_checks_size_limit = 51200
bounce_notice_recipient = postmaster
bounce_queue_lifetime = 5d
bounce_service_name = bounce
bounce_size_limit = 50000
bounce_template_file =
broken_sasl_auth_clients = no
canonical_classes = envelope_sender, envelope_recipient, header_sender, header_recipient
canonical_maps =
cleanup_service_name = cleanup
command_directory = /usr/sbin
command_execution_directory =
command_expansion_filter = 1234567890!@%-_=+:,./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
command_time_limit = 1000s
compatibility_level = 0
config_directory = /etc/postfix
confirm_delay_cleared = no
connection_cache_protocol_timeout = 5s
connection_cache_service_name = scache
connection_cache_status_update_time = 600s
connection_cache_ttl_limit = 2s
content_filter =
cyrus_sasl_config_path =
daemon_directory = /usr/libexec/postfix
daemon_table_open_error_is_fatal = no
daemon_timeout = 18000s
data_directory = /var/lib/postfix
debug_peer_level = 2
debug_peer_list =
debugger_command =
default_database_type = hash
default_delivery_slot_cost = 5
default_delivery_slot_discount = 50
default_delivery_slot_loan = 3
default_delivery_status_filter =
default_destination_concurrency_failed_cohort_limit = 1
default_destination_concurrency_limit = 20
default_destination_concurrency_negative_feedback = 1
default_destination_concurrency_positive_feedback = 1
default_destination_rate_delay = 0s
default_destination_recipient_limit = 50
default_extra_recipient_limit = 1000
default_filter_nexthop =
default_minimum_delivery_slots = 3
default_privs = nobody
default_process_limit = 100
default_rbl_reply = $rbl_code Service unavailable; $rbl_class [$rbl_what] blocked using $rbl_domain${rbl_reason?; $rbl_reason}
default_recipient_limit = 20000
default_recipient_refill_delay = 5s
default_recipient_refill_limit = 100
default_transport = smtp
default_transport_rate_delay = 0s
default_verp_delimiters = +=
defer_code = 450
defer_service_name = defer
defer_transports =
delay_logging_resolution_limit = 2
delay_notice_recipient = postmaster
delay_warning_time = 0h
deliver_lock_attempts = 20
deliver_lock_delay = 1s
destination_concurrency_feedback_debug = no
detect_8bit_encoding_header = yes
disable_dns_lookups = no
disable_mime_input_processing = no
disable_mime_output_conversion = no
disable_verp_bounces = no
disable_vrfy_command = no
dns_ncache_ttl_fix_enable = no
dnsblog_reply_delay = 0s
dnsblog_service_name = dnsblog
dont_remove = 0
double_bounce_sender = double-bounce
duplicate_filter_limit = 1000
empty_address_default_transport_maps_lookup_key = <>
empty_address_recipient = MAILER-DAEMON
empty_address_relayhost_maps_lookup_key = <>
enable_idna2003_compatibility = no
enable_long_queue_ids = no
enable_original_recipient = yes
error_delivery_slot_cost = $default_delivery_slot_cost
error_delivery_slot_discount = $default_delivery_slot_discount
error_delivery_slot_loan = $default_delivery_slot_loan
error_destination_concurrency_failed_cohort_limit = $default_destination_concurrency_failed_cohort_limit
error_destination_concurrency_limit = $default_destination_concurrency_limit
error_destination_concurrency_negative_feedback = $default_destination_concurrency_negative_feedback
error_destination_concurrency_positive_feedback = $default_destination_concurrency_positive_feedback
error_destination_rate_delay = $default_destination_rate_delay
error_destination_recipient_limit = $default_destination_recipient_limit
error_extra_recipient_limit = $default_extra_recipient_limit
error_initial_destination_concurrency = $initial_destination_concurrency
error_minimum_delivery_slots = $default_minimum_delivery_slots
error_notice_recipient = postmaster
error_recipient_limit = $default_recipient_limit
error_recipient_refill_delay = $default_recipient_refill_delay
error_recipient_refill_limit = $default_recipient_refill_limit
error_service_name = error
error_transport_rate_delay = $default_transport_rate_delay
execution_directory_expansion_filter = 1234567890!@%-_=+:,./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
expand_owner_alias = no
export_environment = TZ MAIL_CONFIG LANG
fallback_transport =
fallback_transport_maps =
fast_flush_domains = $relay_domains
fast_flush_purge_time = 7d
fast_flush_refresh_time = 12h
fault_injection_code = 0
flush_service_name = flush
fork_attempts = 5
fork_delay = 1s
forward_expansion_filter = 1234567890!@%-_=+:,./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
forward_path = $home/.forward${recipient_delimiter}${extension}, $home/.forward
frozen_delivered_to = yes
hash_queue_depth = 1
hash_queue_names = deferred, defer
header_address_token_limit = 10240
header_checks =
header_from_format = standard
header_size_limit = 102400
helpful_warnings = yes
home_mailbox =
hopcount_limit = 50
html_directory = no
ignore_mx_lookup_error = no
import_environment = MAIL_CONFIG MAIL_DEBUG MAIL_LOGTAG TZ XAUTHORITY DISPLAY LANG=C
in_flow_delay = 1s
inet_interfaces = all
inet_protocols = all
initial_destination_concurrency = 5
internal_mail_filter_classes =
invalid_hostname_reject_code = 501
ipc_idle = 5s
ipc_timeout = 3600s
ipc_ttl = 1000s
line_length_limit = 2048
lmdb_map_size = 16777216
lmtp_address_preference = any
lmtp_address_verify_target = rcpt
lmtp_assume_final = no
lmtp_balance_inet_protocols = yes
lmtp_bind_address =
lmtp_bind_address6 =
lmtp_body_checks =
lmtp_cname_overrides_servername = no
lmtp_connect_timeout = 0s
lmtp_connection_cache_destinations =
lmtp_connection_cache_on_demand = yes
lmtp_connection_cache_time_limit = 2s
lmtp_connection_reuse_count_limit = 0
lmtp_connection_reuse_time_limit = 300s
lmtp_data_done_timeout = 600s
lmtp_data_init_timeout = 120s
lmtp_data_xfer_timeout = 180s
lmtp_defer_if_no_mx_address_found = no
lmtp_delivery_slot_cost = $default_delivery_slot_cost
lmtp_delivery_slot_discount = $default_delivery_slot_discount
lmtp_delivery_slot_loan = $default_delivery_slot_loan
lmtp_delivery_status_filter = $default_delivery_status_filter
lmtp_destination_concurrency_failed_cohort_limit = $default_destination_concurrency_failed_cohort_limit
lmtp_destination_concurrency_limit = $default_destination_concurrency_limit
lmtp_destination_concurrency_negative_feedback = $default_destination_concurrency_negative_feedback
lmtp_destination_concurrency_positive_feedback = $default_destination_concurrency_positive_feedback
lmtp_destination_rate_delay = $default_destination_rate_delay
lmtp_destination_recipient_limit = $default_destination_recipient_limit
lmtp_discard_lhlo_keyword_address_maps =
lmtp_discard_lhlo_keywords =
lmtp_dns_reply_filter =
lmtp_dns_resolver_options =
lmtp_dns_support_level =
lmtp_enforce_tls = no
lmtp_extra_recipient_limit = $default_extra_recipient_limit
lmtp_fallback_relay =
lmtp_generic_maps =
lmtp_header_checks =
lmtp_host_lookup = dns
lmtp_initial_destination_concurrency = $initial_destination_concurrency
lmtp_lhlo_name = $myhostname
lmtp_lhlo_timeout = 300s
lmtp_line_length_limit = 998
lmtp_mail_timeout = 300s
lmtp_mime_header_checks =
lmtp_minimum_delivery_slots = $default_minimum_delivery_slots
lmtp_mx_address_limit = 5
lmtp_mx_session_limit = 2
lmtp_nested_header_checks =
lmtp_per_record_deadline = no
lmtp_pix_workaround_delay_time = 10s
lmtp_pix_workaround_maps =
lmtp_pix_workaround_threshold_time = 500s
lmtp_pix_workarounds = disable_esmtp,delay_dotcrlf
lmtp_quit_timeout = 300s
lmtp_quote_rfc821_envelope = yes
lmtp_randomize_addresses = yes
lmtp_rcpt_timeout = 300s
lmtp_recipient_limit = $default_recipient_limit
lmtp_recipient_refill_delay = $default_recipient_refill_delay
lmtp_recipient_refill_limit = $default_recipient_refill_limit
lmtp_reply_filter =
lmtp_rset_timeout = 20s
lmtp_sasl_auth_cache_name =
lmtp_sasl_auth_cache_time = 90d
lmtp_sasl_auth_enable = no
lmtp_sasl_auth_soft_bounce = yes
lmtp_sasl_mechanism_filter =
lmtp_sasl_password_maps =
lmtp_sasl_path =
lmtp_sasl_security_options = noplaintext, noanonymous
lmtp_sasl_tls_security_options = $lmtp_sasl_security_options
lmtp_sasl_tls_verified_security_options = $lmtp_sasl_tls_security_options
lmtp_sasl_type = cyrus
lmtp_send_dummy_mail_auth = no
lmtp_send_xforward_command = no
lmtp_sender_dependent_authentication = no
lmtp_skip_5xx_greeting = yes
lmtp_skip_quit_response = no
lmtp_starttls_timeout = 300s
lmtp_tcp_port = 24
lmtp_tls_CAfile =
lmtp_tls_CApath =
lmtp_tls_block_early_mail_reply = no
lmtp_tls_cert_file =
lmtp_tls_ciphers = medium
lmtp_tls_dcert_file =
lmtp_tls_dkey_file = $lmtp_tls_dcert_file
lmtp_tls_eccert_file =
lmtp_tls_eckey_file = $lmtp_tls_eccert_file
lmtp_tls_enforce_peername = yes
lmtp_tls_exclude_ciphers =
lmtp_tls_fingerprint_cert_match =
lmtp_tls_fingerprint_digest = md5
lmtp_tls_force_insecure_host_tlsa_lookup = no
lmtp_tls_key_file = $lmtp_tls_cert_file
lmtp_tls_loglevel = 0
lmtp_tls_mandatory_ciphers = medium
lmtp_tls_mandatory_exclude_ciphers =
lmtp_tls_mandatory_protocols = !SSLv2, !SSLv3
lmtp_tls_note_starttls_offer = no
lmtp_tls_per_site =
lmtp_tls_policy_maps =
lmtp_tls_protocols = !SSLv2, !SSLv3
lmtp_tls_scert_verifydepth = 9
lmtp_tls_secure_cert_match = nexthop
lmtp_tls_security_level =
lmtp_tls_session_cache_database =
lmtp_tls_session_cache_timeout = 3600s
lmtp_tls_trust_anchor_file =
lmtp_tls_verify_cert_match = hostname
lmtp_tls_wrappermode = no
lmtp_transport_rate_delay = $default_transport_rate_delay
lmtp_use_tls = no
lmtp_xforward_timeout = 300s
local_command_shell =
local_delivery_slot_cost = $default_delivery_slot_cost
local_delivery_slot_discount = $default_delivery_slot_discount
local_delivery_slot_loan = $default_delivery_slot_loan
local_delivery_status_filter = $default_delivery_status_filter
local_destination_concurrency_failed_cohort_limit = $default_destination_concurrency_failed_cohort_limit
local_destination_concurrency_limit = 2
local_destination_concurrency_negative_feedback = $default_destination_concurrency_negative_feedback
local_destination_concurrency_positive_feedback = $default_destination_concurrency_positive_feedback
local_destination_rate_delay = $default_destination_rate_delay
local_destination_recipient_limit = 1
local_extra_recipient_limit = $default_extra_recipient_limit
local_header_rewrite_clients = permit_inet_interfaces
local_initial_destination_concurrency = $initial_destination_concurrency
local_minimum_delivery_slots = $default_minimum_delivery_slots
local_recipient_limit = $default_recipient_limit
local_recipient_maps = proxy:unix:passwd.byname $alias_maps
local_recipient_refill_delay = $default_recipient_refill_delay
local_recipient_refill_limit = $default_recipient_refill_limit
local_transport = local:$myhostname
local_transport_rate_delay = $default_transport_rate_delay
luser_relay =
mail_name = Postfix
mail_owner = postfix
mail_release_date = 20181124
mail_spool_directory = /var/mail
mail_version = 3.3.2
mailbox_command =
mailbox_command_maps =
mailbox_delivery_lock = fcntl, dotlock
mailbox_size_limit = 51200000
mailbox_transport =
mailbox_transport_maps =
mailq_path = /usr/bin/mailq
manpage_directory = /usr/local/man
maps_rbl_domains =
maps_rbl_reject_code = 554
masquerade_classes = envelope_sender, header_sender, header_recipient
masquerade_domains =
masquerade_exceptions =
master_service_disable =
max_idle = 100s
max_use = 100
maximal_backoff_time = 4000s
maximal_queue_lifetime = 5d
message_drop_headers = bcc, content-length, resent-bcc, return-path
message_reject_characters =
message_size_limit = 10240000
message_strip_characters =
meta_directory = /etc/postfix
milter_command_timeout = 30s
milter_connect_macros = j {daemon_name} {daemon_addr} v
milter_connect_timeout = 30s
milter_content_timeout = 300s
milter_data_macros = i
milter_default_action = tempfail
milter_end_of_data_macros = i
milter_end_of_header_macros = i
milter_header_checks =
milter_helo_macros = {tls_version} {cipher} {cipher_bits} {cert_subject} {cert_issuer}
milter_macro_daemon_name = $myhostname
milter_macro_defaults =
milter_macro_v = $mail_name $mail_version
milter_mail_macros = i {auth_type} {auth_authen} {auth_author} {mail_addr} {mail_host} {mail_mailer}
milter_protocol = 6
milter_rcpt_macros = i {rcpt_addr} {rcpt_host} {rcpt_mailer}
milter_unknown_command_macros =
mime_boundary_length_limit = 2048
mime_header_checks = $header_checks
mime_nesting_limit = 100
minimal_backoff_time = 300s
multi_instance_directories =
multi_instance_enable = no
multi_instance_group =
multi_instance_name =
multi_instance_wrapper =
multi_recipient_bounce_reject_code = 550
mydestination = $myhostname, localhost.$mydomain, localhost
mydomain = dmz.nausch.org
myhostname = vml000080.dmz.nausch.org
mynetworks = 127.0.0.0/8 10.0.0.0/24 [::1]/128 [fe80::]/64
mynetworks_style = ${{$compatibility_level} < {2} ? {subnet} : {host}}
myorigin = $myhostname
nested_header_checks = $header_checks
newaliases_path = /usr/bin/newaliases
non_fqdn_reject_code = 504
non_smtpd_milters =
notify_classes = resource, software
openssl_path = openssl
owner_request_special = yes
parent_domain_matches_subdomains = debug_peer_list,fast_flush_domains,mynetworks,permit_mx_backup_networks,qmqpd_authorized_clients,relay_domains,smtpd_access_maps
permit_mx_backup_networks =
pickup_service_name = pickup
pipe_delivery_status_filter = $default_delivery_status_filter
plaintext_reject_code = 450
postmulti_control_commands = reload flush
postmulti_start_commands = start
postmulti_stop_commands = stop abort drain quick-stop
postscreen_access_list = permit_mynetworks
postscreen_bare_newline_action = ignore
postscreen_bare_newline_enable = no
postscreen_bare_newline_ttl = 30d
postscreen_blacklist_action = ignore
postscreen_cache_cleanup_interval = 12h
postscreen_cache_map = btree:$data_directory/postscreen_cache
postscreen_cache_retention_time = 7d
postscreen_client_connection_count_limit = $smtpd_client_connection_count_limit
postscreen_command_count_limit = 20
postscreen_command_filter =
postscreen_command_time_limit = ${stress?{10}:{300}}s
postscreen_disable_vrfy_command = $disable_vrfy_command
postscreen_discard_ehlo_keyword_address_maps = $smtpd_discard_ehlo_keyword_address_maps
postscreen_discard_ehlo_keywords = $smtpd_discard_ehlo_keywords
postscreen_dnsbl_action = ignore
postscreen_dnsbl_max_ttl = ${postscreen_dnsbl_ttl?{$postscreen_dnsbl_ttl}:{1}}h
postscreen_dnsbl_min_ttl = 60s
postscreen_dnsbl_reply_map =
postscreen_dnsbl_sites =
postscreen_dnsbl_threshold = 1
postscreen_dnsbl_timeout = 10s
postscreen_dnsbl_whitelist_threshold = 0
postscreen_enforce_tls = $smtpd_enforce_tls
postscreen_expansion_filter = $smtpd_expansion_filter
postscreen_forbidden_commands = $smtpd_forbidden_commands
postscreen_greet_action = ignore
postscreen_greet_banner = $smtpd_banner
postscreen_greet_ttl = 1d
postscreen_greet_wait = ${stress?{2}:{6}}s
postscreen_helo_required = $smtpd_helo_required
postscreen_non_smtp_command_action = drop
postscreen_non_smtp_command_enable = no
postscreen_non_smtp_command_ttl = 30d
postscreen_pipelining_action = enforce
postscreen_pipelining_enable = no
postscreen_pipelining_ttl = 30d
postscreen_post_queue_limit = $default_process_limit
postscreen_pre_queue_limit = $default_process_limit
postscreen_reject_footer = $smtpd_reject_footer
postscreen_tls_security_level = $smtpd_tls_security_level
postscreen_upstream_proxy_protocol =
postscreen_upstream_proxy_timeout = 5s
postscreen_use_tls = $smtpd_use_tls
postscreen_watchdog_timeout = 10s
postscreen_whitelist_interfaces = static:all
prepend_delivered_header = command, file, forward
process_id = 14166
process_id_directory = pid
process_name = postconf
propagate_unmatched_extensions = canonical, virtual
proxy_interfaces =
proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks $smtpd_sender_login_maps $sender_bcc_maps $recipient_bcc_maps $smtp_generic_maps $lmtp_generic_maps $alias_maps $smtpd_client_restrictions $smtpd_helo_restrictions $smtpd_sender_restrictions $smtpd_relay_restrictions $smtpd_recipient_restrictions $address_verify_sender_dependent_default_transport_maps $address_verify_sender_dependent_relayhost_maps $address_verify_transport_maps $fallback_transport_maps $lmtp_discard_lhlo_keyword_address_maps $lmtp_pix_workaround_maps $lmtp_sasl_password_maps $lmtp_tls_policy_maps $mailbox_command_maps $mailbox_transport_maps $postscreen_discard_ehlo_keyword_address_maps $rbl_reply_maps $sender_dependent_default_transport_maps $sender_dependent_relayhost_maps $smtp_discard_ehlo_keyword_address_maps $smtp_pix_workaround_maps $smtp_sasl_password_maps $smtp_tls_policy_maps $smtpd_discard_ehlo_keyword_address_maps $smtpd_milter_maps $virtual_gid_maps $virtual_uid_maps
proxy_write_maps = $smtp_sasl_auth_cache_name $lmtp_sasl_auth_cache_name $address_verify_map $postscreen_cache_map
proxymap_service_name = proxymap
proxywrite_service_name = proxywrite
qmgr_clog_warn_time = 300s
qmgr_daemon_timeout = 1000s
qmgr_fudge_factor = 100
qmgr_ipc_timeout = 60s
qmgr_message_active_limit = 20000
qmgr_message_recipient_limit = 20000
qmgr_message_recipient_minimum = 10
qmqpd_authorized_clients =
qmqpd_client_port_logging = no
qmqpd_error_delay = 1s
qmqpd_timeout = 300s
queue_directory = /var/spool/postfix
queue_file_attribute_count_limit = 100
queue_minfree = 0
queue_run_delay = 300s
queue_service_name = qmgr
rbl_reply_maps =
readme_directory = no
receive_override_options =
recipient_bcc_maps =
recipient_canonical_classes = envelope_recipient, header_recipient
recipient_canonical_maps =
recipient_delimiter =
reject_code = 554
reject_tempfail_action = defer_if_permit
relay_clientcerts =
relay_delivery_slot_cost = $default_delivery_slot_cost
relay_delivery_slot_discount = $default_delivery_slot_discount
relay_delivery_slot_loan = $default_delivery_slot_loan
relay_destination_concurrency_failed_cohort_limit = $default_destination_concurrency_failed_cohort_limit
relay_destination_concurrency_limit = $default_destination_concurrency_limit
relay_destination_concurrency_negative_feedback = $default_destination_concurrency_negative_feedback
relay_destination_concurrency_positive_feedback = $default_destination_concurrency_positive_feedback
relay_destination_rate_delay = $default_destination_rate_delay
relay_destination_recipient_limit = $default_destination_recipient_limit
relay_domains = ${{$compatibility_level} < {2} ? {$mydestination} : {}}
relay_domains_reject_code = 554
relay_extra_recipient_limit = $default_extra_recipient_limit
relay_initial_destination_concurrency = $initial_destination_concurrency
relay_minimum_delivery_slots = $default_minimum_delivery_slots
relay_recipient_limit = $default_recipient_limit
relay_recipient_maps =
relay_recipient_refill_delay = $default_recipient_refill_delay
relay_recipient_refill_limit = $default_recipient_refill_limit
relay_transport = relay
relay_transport_rate_delay = $default_transport_rate_delay
relayhost =
relocated_maps =
remote_header_rewrite_domain =
require_home_directory = no
reset_owner_alias = no
resolve_dequoted_address = yes
resolve_null_domain = no
resolve_numeric_domain = no
retry_delivery_slot_cost = $default_delivery_slot_cost
retry_delivery_slot_discount = $default_delivery_slot_discount
retry_delivery_slot_loan = $default_delivery_slot_loan
retry_destination_concurrency_failed_cohort_limit = $default_destination_concurrency_failed_cohort_limit
retry_destination_concurrency_limit = $default_destination_concurrency_limit
retry_destination_concurrency_negative_feedback = $default_destination_concurrency_negative_feedback
retry_destination_concurrency_positive_feedback = $default_destination_concurrency_positive_feedback
retry_destination_rate_delay = $default_destination_rate_delay
retry_destination_recipient_limit = $default_destination_recipient_limit
retry_extra_recipient_limit = $default_extra_recipient_limit
retry_initial_destination_concurrency = $initial_destination_concurrency
retry_minimum_delivery_slots = $default_minimum_delivery_slots
retry_recipient_limit = $default_recipient_limit
retry_recipient_refill_delay = $default_recipient_refill_delay
retry_recipient_refill_limit = $default_recipient_refill_limit
retry_transport_rate_delay = $default_transport_rate_delay
rewrite_service_name = rewrite
sample_directory = /etc/postfix
send_cyrus_sasl_authzid = no
sender_bcc_maps =
sender_canonical_classes = envelope_sender, header_sender
sender_canonical_maps =
sender_dependent_default_transport_maps =
sender_dependent_relayhost_maps =
sendmail_fix_line_endings = always
sendmail_path = /usr/sbin/sendmail
service_name =
service_throttle_time = 60s
setgid_group = postdrop
shlib_directory = /usr/lib/postfix
show_user_unknown_table_name = yes
showq_service_name = showq
smtp_address_preference = any
smtp_address_verify_target = rcpt
smtp_always_send_ehlo = yes
smtp_balance_inet_protocols = yes
smtp_bind_address =
smtp_bind_address6 =
smtp_body_checks =
smtp_cname_overrides_servername = no
smtp_connect_timeout = 30s
smtp_connection_cache_destinations =
smtp_connection_cache_on_demand = yes
smtp_connection_cache_time_limit = 2s
smtp_connection_reuse_count_limit = 0
smtp_connection_reuse_time_limit = 300s
smtp_data_done_timeout = 600s
smtp_data_init_timeout = 120s
smtp_data_xfer_timeout = 180s
smtp_defer_if_no_mx_address_found = no
smtp_delivery_slot_cost = $default_delivery_slot_cost
smtp_delivery_slot_discount = $default_delivery_slot_discount
smtp_delivery_slot_loan = $default_delivery_slot_loan
smtp_delivery_status_filter = $default_delivery_status_filter
smtp_destination_concurrency_failed_cohort_limit = $default_destination_concurrency_failed_cohort_limit
smtp_destination_concurrency_limit = $default_destination_concurrency_limit
smtp_destination_concurrency_negative_feedback = $default_destination_concurrency_negative_feedback
smtp_destination_concurrency_positive_feedback = $default_destination_concurrency_positive_feedback
smtp_destination_rate_delay = $default_destination_rate_delay
smtp_destination_recipient_limit = $default_destination_recipient_limit
smtp_discard_ehlo_keyword_address_maps =
smtp_discard_ehlo_keywords =
smtp_dns_reply_filter =
smtp_dns_resolver_options =
smtp_dns_support_level =
smtp_enforce_tls = no
smtp_extra_recipient_limit = $default_extra_recipient_limit
smtp_fallback_relay = $fallback_relay
smtp_generic_maps =
smtp_header_checks =
smtp_helo_name = $myhostname
smtp_helo_timeout = 300s
smtp_host_lookup = dns
smtp_initial_destination_concurrency = $initial_destination_concurrency
smtp_line_length_limit = 998
smtp_mail_timeout = 300s
smtp_mime_header_checks =
smtp_minimum_delivery_slots = $default_minimum_delivery_slots
smtp_mx_address_limit = 5
smtp_mx_session_limit = 2
smtp_nested_header_checks =
smtp_never_send_ehlo = no
smtp_per_record_deadline = no
smtp_pix_workaround_delay_time = 10s
smtp_pix_workaround_maps =
smtp_pix_workaround_threshold_time = 500s
smtp_pix_workarounds = disable_esmtp,delay_dotcrlf
smtp_quit_timeout = 300s
smtp_quote_rfc821_envelope = yes
smtp_randomize_addresses = yes
smtp_rcpt_timeout = 300s
smtp_recipient_limit = $default_recipient_limit
smtp_recipient_refill_delay = $default_recipient_refill_delay
smtp_recipient_refill_limit = $default_recipient_refill_limit
smtp_reply_filter =
smtp_rset_timeout = 20s
smtp_sasl_auth_cache_name =
smtp_sasl_auth_cache_time = 90d
smtp_sasl_auth_enable = no
smtp_sasl_auth_soft_bounce = yes
smtp_sasl_mechanism_filter =
smtp_sasl_password_maps =
smtp_sasl_path =
smtp_sasl_security_options = noplaintext, noanonymous
smtp_sasl_tls_security_options = $smtp_sasl_security_options
smtp_sasl_tls_verified_security_options = $smtp_sasl_tls_security_options
smtp_sasl_type = cyrus
smtp_send_dummy_mail_auth = no
smtp_send_xforward_command = no
smtp_sender_dependent_authentication = no
smtp_skip_5xx_greeting = yes
smtp_skip_quit_response = yes
smtp_starttls_timeout = 300s
smtp_tcp_port = smtp
smtp_tls_CAfile =
smtp_tls_CApath =
smtp_tls_block_early_mail_reply = no
smtp_tls_cert_file =
smtp_tls_ciphers = medium
smtp_tls_dane_insecure_mx_policy = dane
smtp_tls_dcert_file =
smtp_tls_dkey_file = $smtp_tls_dcert_file
smtp_tls_eccert_file =
smtp_tls_eckey_file = $smtp_tls_eccert_file
smtp_tls_enforce_peername = yes
smtp_tls_exclude_ciphers =
smtp_tls_fingerprint_cert_match =
smtp_tls_fingerprint_digest = md5
smtp_tls_force_insecure_host_tlsa_lookup = no
smtp_tls_key_file = $smtp_tls_cert_file
smtp_tls_loglevel = 0
smtp_tls_mandatory_ciphers = medium
smtp_tls_mandatory_exclude_ciphers =
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3
smtp_tls_note_starttls_offer = no
smtp_tls_per_site =
smtp_tls_policy_maps =
smtp_tls_protocols = !SSLv2, !SSLv3
smtp_tls_scert_verifydepth = 9
smtp_tls_secure_cert_match = nexthop, dot-nexthop
smtp_tls_security_level =
smtp_tls_session_cache_database =
smtp_tls_session_cache_timeout = 3600s
smtp_tls_trust_anchor_file =
smtp_tls_verify_cert_match = hostname
smtp_tls_wrappermode = no
smtp_transport_rate_delay = $default_transport_rate_delay
smtp_use_tls = no
smtp_xforward_timeout = 300s
smtpd_authorized_verp_clients = $authorized_verp_clients
smtpd_authorized_xclient_hosts =
smtpd_authorized_xforward_hosts =
smtpd_banner = $myhostname ESMTP $mail_name
smtpd_client_auth_rate_limit = 0
smtpd_client_connection_count_limit = 50
smtpd_client_connection_rate_limit = 0
smtpd_client_event_limit_exceptions = ${smtpd_client_connection_limit_exceptions:$mynetworks}
smtpd_client_message_rate_limit = 0
smtpd_client_new_tls_session_rate_limit = 0
smtpd_client_port_logging = no
smtpd_client_recipient_rate_limit = 0
smtpd_client_restrictions =
smtpd_command_filter =
smtpd_data_restrictions =
smtpd_delay_open_until_valid_rcpt = yes
smtpd_delay_reject = yes
smtpd_discard_ehlo_keyword_address_maps =
smtpd_discard_ehlo_keywords =
smtpd_dns_reply_filter =
smtpd_end_of_data_restrictions =
smtpd_enforce_tls = no
smtpd_error_sleep_time = 1s
smtpd_etrn_restrictions =
smtpd_expansion_filter = \t\40!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~
smtpd_forbidden_commands = CONNECT GET POST
smtpd_hard_error_limit = ${stress?{1}:{20}}
smtpd_helo_required = no
smtpd_helo_restrictions =
smtpd_history_flush_threshold = 100
smtpd_junk_command_limit = ${stress?{1}:{100}}
smtpd_log_access_permit_actions =
smtpd_milter_maps =
smtpd_milters =
smtpd_noop_commands =
smtpd_null_access_lookup_key = <>
smtpd_peername_lookup = yes
smtpd_per_record_deadline = ${stress?{yes}:{no}}
smtpd_policy_service_default_action = 451 4.3.5 Server configuration problem
smtpd_policy_service_max_idle = 300s
smtpd_policy_service_max_ttl = 1000s
smtpd_policy_service_policy_context =
smtpd_policy_service_request_limit = 0
smtpd_policy_service_retry_delay = 1s
smtpd_policy_service_timeout = 100s
smtpd_policy_service_try_limit = 2
smtpd_proxy_ehlo = $myhostname
smtpd_proxy_filter =
smtpd_proxy_options =
smtpd_proxy_timeout = 100s
smtpd_recipient_limit = 1000
smtpd_recipient_overshoot_limit = 1000
smtpd_recipient_restrictions =
smtpd_reject_footer =
smtpd_reject_unlisted_recipient = yes
smtpd_reject_unlisted_sender = no
smtpd_relay_restrictions = ${{$compatibility_level} < {1} ? {} : {permit_mynetworks, permit_sasl_authenticated, defer_unauth_destination}}
smtpd_restriction_classes =
smtpd_sasl_auth_enable = no
smtpd_sasl_authenticated_header = no
smtpd_sasl_exceptions_networks =
smtpd_sasl_local_domain =
smtpd_sasl_path = smtpd
smtpd_sasl_security_options = noanonymous
smtpd_sasl_service = smtp
smtpd_sasl_tls_security_options = $smtpd_sasl_security_options
smtpd_sasl_type = cyrus
smtpd_sender_login_maps =
smtpd_sender_restrictions =
smtpd_service_name = smtpd
smtpd_soft_error_limit = 10
smtpd_starttls_timeout = ${stress?{10}:{300}}s
smtpd_timeout = ${stress?{10}:{300}}s
smtpd_tls_CAfile =
smtpd_tls_CApath =
smtpd_tls_always_issue_session_ids = yes
smtpd_tls_ask_ccert = no
smtpd_tls_auth_only = no
smtpd_tls_ccert_verifydepth = 9
smtpd_tls_cert_file =
smtpd_tls_ciphers = medium
smtpd_tls_dcert_file =
smtpd_tls_dh1024_param_file =
smtpd_tls_dh512_param_file =
smtpd_tls_dkey_file = $smtpd_tls_dcert_file
smtpd_tls_eccert_file =
smtpd_tls_eckey_file = $smtpd_tls_eccert_file
smtpd_tls_eecdh_grade = auto
smtpd_tls_exclude_ciphers =
smtpd_tls_fingerprint_digest = md5
smtpd_tls_key_file = $smtpd_tls_cert_file
smtpd_tls_loglevel = 0
smtpd_tls_mandatory_ciphers = medium
smtpd_tls_mandatory_exclude_ciphers =
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_protocols = !SSLv2, !SSLv3
smtpd_tls_received_header = no
smtpd_tls_req_ccert = no
smtpd_tls_security_level =
smtpd_tls_session_cache_database =
smtpd_tls_session_cache_timeout = 3600s
smtpd_tls_wrappermode = no
smtpd_upstream_proxy_protocol =
smtpd_upstream_proxy_timeout = 5s
smtpd_use_tls = no
smtputf8_autodetect_classes = sendmail, verify
smtputf8_enable = ${{$compatibility_level} < {1} ? {no} : {yes}}
soft_bounce = no
stale_lock_time = 500s
stress =
strict_7bit_headers = no
strict_8bitmime = no
strict_8bitmime_body = no
strict_mailbox_ownership = yes
strict_mime_encoding_domain = no
strict_rfc821_envelopes = no
strict_smtputf8 = no
sun_mailtool_compatibility = no
swap_bangpath = yes
syslog_facility = mail
syslog_name = ${multi_instance_name?{$multi_instance_name}:{postfix}}
tcp_windowsize = 0
tls_append_default_CA = no
tls_daemon_random_bytes = 32
tls_dane_digest_agility = on
tls_dane_digests = sha512 sha256
tls_dane_trust_anchor_digest_enable = yes
tls_disable_workarounds =
tls_eecdh_auto_curves = prime256v1 secp521r1 secp384r1
tls_eecdh_strong_curve = prime256v1
tls_eecdh_ultra_curve = secp384r1
tls_export_cipherlist = aNULL:-aNULL:HIGH:MEDIUM:LOW:EXPORT:+RC4:@STRENGTH
tls_high_cipherlist = aNULL:-aNULL:HIGH:@STRENGTH
tls_legacy_public_key_fingerprints = no
tls_low_cipherlist = aNULL:-aNULL:HIGH:MEDIUM:LOW:+RC4:@STRENGTH
tls_medium_cipherlist = aNULL:-aNULL:HIGH:MEDIUM:+RC4:@STRENGTH
tls_null_cipherlist = eNULL:!aNULL
tls_preempt_cipherlist = no
tls_random_bytes = 32
tls_random_exchange_name = ${data_directory}/prng_exch
tls_random_prng_update_period = 3600s
tls_random_reseed_period = 3600s
tls_random_source = dev:/dev/urandom
tls_session_ticket_cipher = aes-256-cbc
tls_ssl_options =
tls_wildcard_matches_multiple_labels = yes
tlsmgr_service_name = tlsmgr
tlsproxy_enforce_tls = $smtpd_enforce_tls
tlsproxy_service_name = tlsproxy
tlsproxy_tls_CAfile = $smtpd_tls_CAfile
tlsproxy_tls_CApath = $smtpd_tls_CApath
tlsproxy_tls_always_issue_session_ids = $smtpd_tls_always_issue_session_ids
tlsproxy_tls_ask_ccert = $smtpd_tls_ask_ccert
tlsproxy_tls_ccert_verifydepth = $smtpd_tls_ccert_verifydepth
tlsproxy_tls_cert_file = $smtpd_tls_cert_file
tlsproxy_tls_ciphers = $smtpd_tls_ciphers
tlsproxy_tls_dcert_file = $smtpd_tls_dcert_file
tlsproxy_tls_dh1024_param_file = $smtpd_tls_dh1024_param_file
tlsproxy_tls_dh512_param_file = $smtpd_tls_dh512_param_file
tlsproxy_tls_dkey_file = $smtpd_tls_dkey_file
tlsproxy_tls_eccert_file = $smtpd_tls_eccert_file
tlsproxy_tls_eckey_file = $smtpd_tls_eckey_file
tlsproxy_tls_eecdh_grade = $smtpd_tls_eecdh_grade
tlsproxy_tls_exclude_ciphers = $smtpd_tls_exclude_ciphers
tlsproxy_tls_fingerprint_digest = $smtpd_tls_fingerprint_digest
tlsproxy_tls_key_file = $smtpd_tls_key_file
tlsproxy_tls_loglevel = $smtpd_tls_loglevel
tlsproxy_tls_mandatory_ciphers = $smtpd_tls_mandatory_ciphers
tlsproxy_tls_mandatory_exclude_ciphers = $smtpd_tls_mandatory_exclude_ciphers
tlsproxy_tls_mandatory_protocols = $smtpd_tls_mandatory_protocols
tlsproxy_tls_protocols = $smtpd_tls_protocols
tlsproxy_tls_req_ccert = $smtpd_tls_req_ccert
tlsproxy_tls_security_level = $smtpd_tls_security_level
tlsproxy_use_tls = $smtpd_use_tls
tlsproxy_watchdog_timeout = 10s
trace_service_name = trace
transport_maps =
transport_retry_time = 60s
trigger_timeout = 10s
undisclosed_recipients_header =
unknown_address_reject_code = 450
unknown_address_tempfail_action = $reject_tempfail_action
unknown_client_reject_code = 450
unknown_helo_hostname_tempfail_action = $reject_tempfail_action
unknown_hostname_reject_code = 450
unknown_local_recipient_reject_code = 550
unknown_relay_recipient_reject_code = 550
unknown_virtual_alias_reject_code = 550
unknown_virtual_mailbox_reject_code = 550
unverified_recipient_defer_code = 450
unverified_recipient_reject_code = 450
unverified_recipient_reject_reason =
unverified_recipient_tempfail_action = $reject_tempfail_action
unverified_sender_defer_code = 450
unverified_sender_reject_code = 450
unverified_sender_reject_reason =
unverified_sender_tempfail_action = $reject_tempfail_action
verp_delimiter_filter = -=+
virtual_alias_address_length_limit = 1000
virtual_alias_domains = $virtual_alias_maps
virtual_alias_expansion_limit = 1000
virtual_alias_maps = $virtual_maps
virtual_alias_recursion_limit = 1000
virtual_delivery_slot_cost = $default_delivery_slot_cost
virtual_delivery_slot_discount = $default_delivery_slot_discount
virtual_delivery_slot_loan = $default_delivery_slot_loan
virtual_delivery_status_filter = $default_delivery_status_filter
virtual_destination_concurrency_failed_cohort_limit = $default_destination_concurrency_failed_cohort_limit
virtual_destination_concurrency_limit = $default_destination_concurrency_limit
virtual_destination_concurrency_negative_feedback = $default_destination_concurrency_negative_feedback
virtual_destination_concurrency_positive_feedback = $default_destination_concurrency_positive_feedback
virtual_destination_rate_delay = $default_destination_rate_delay
virtual_destination_recipient_limit = $default_destination_recipient_limit
virtual_extra_recipient_limit = $default_extra_recipient_limit
virtual_gid_maps =
virtual_initial_destination_concurrency = $initial_destination_concurrency
virtual_mailbox_base =
virtual_mailbox_domains = $virtual_mailbox_maps
virtual_mailbox_limit = 51200000
virtual_mailbox_lock = fcntl, dotlock
virtual_mailbox_maps =
virtual_minimum_delivery_slots = $default_minimum_delivery_slots
virtual_minimum_uid = 100
virtual_recipient_limit = $default_recipient_limit
virtual_recipient_refill_delay = $default_recipient_refill_delay
virtual_recipient_refill_limit = $default_recipient_refill_limit
virtual_transport = virtual
virtual_transport_rate_delay = $default_transport_rate_delay
virtual_uid_maps =

Möchten wir nun einen einzelne Variable abfragen, die nicht den Defaultvorgaben entspricht benutzen wir im Fall von myorigin den folgenden Aufruf.

 # postconf -d myorigin
myorigin = $myhostname

Wollen wir einen Parameter ändern, so benutzen wir die Option -e. Als erstes fragen wir den wert einer Variable, im folgenden Beispiel von smtpd_client_connection_count_limit.

 # postconf -d smtpd_client_connection_count_limit
 smtpd_client_connection_count_limit = 50

Den Defaulwert von 50 ändern wir nun ab auf den Wert 10.

 # postconf -e "smtpd_client_connection_count_limit = 10"

Anschließend muss via systemctl reload postfix der laufende Daemon noch von der Änderung an der main.cf informiert werden.

Auf die wichtigsten Konfigurationsparameter für den Betrieb unseres Mailservers gehen wir nun kurz ein:

  • myhostname
    Definition des Hostnames, über den der Mailserver später erreichbar sein wird. Die IP-Adresse des Mailservers muss später auch reverse auf gelöst werden könnne und dem hier definiertem Hostnamen entsprechen.
  • mydomain
    Definition der eigenen Domäne. Normalerweise, wird man diesen Wert nie setzen müssen, da der Wert automatisch vom Parameter myhostname abgeleitet wird, in dem der Host-Teil abgetrennt wird. Aus myhostname = mx1.nausch.org wird so nausch.org, ohne dasss wir extra Hand anlegen müssen. Den Parameter mydomain wird man also nur setzen müssen, wenn der Wert vom Domain-Teil des Parameters myhostname abweicht!
  • mydestination Über diesen Parameter wird definiert, für welche Domains sich unser Postfix als final destination fühlt; der MTA also eigentlich eMails annehmen soll. Normalerweise wird dies neben dem Wert localhost der Domain und Hostname des Servers sein.
    Der Parameter mydestination beschreibt nur den realen Hostnamen sowie der realen Domäne des Mailservers. Möchte man virtuelle Domänen verwenden, definiert man diese mit Hilfe der virtual-table und nicht bei mydestination!
  • myorigin Werden eMails lokal auf dem Mailserverhost generiert, erzeugt Postfix „richtige eMAiladressen“, in dem der Mailserver den User-Namen bzw. die User-ID mit dem Wert aus $myorigin ergänzt. Der Defaultwert myorigin = $mydomain bewirkt also, dass eine eMail von root auf unserem Host mx1.nausch.org die eMailadresse root@nausch.org erhält. Möchte man z.B. für DMZ-interne eMails in der eMailadresse direkt den Hostnamen mit angeben, so wird man hier statt $mydomain $myhostname angeben; somit würde dann die Adresse logwatch@pml010043.intra.nausch.org statt logwatch@nausch.org generiert.
  • mynetworks
    Muss man mehrere verschiedene Netzbereiche, oder einzelne Hosts zum sicheren Relayen freischalten, dann müssen die einzelnen Netzbereiche, bzw. Hosts über den Parameter mynetworks definiert werden. 10.10.10.0/24 beschreibt so ein ganzes Netz, 10.0.0.10/32 hingegen nur einen einzelnen Host.
  • mynetworks_style
    Festlegung des Netzes oder des Netzbereiches, die unser Postfix als vertrauenswürdig betrachten soll. Host aus diesem Netzbereichen ist es gestattet, eMails an externe Empfänger einzuliefern, die unser MTA dann wiederum ausliefern wird. class, host und subnet (Defaulteinstellung) können hier ausgewählt werden.
  • inet_interfaces
    Festlegung der Netzwerk-Adresse, von denen der Mailserver Verbindungen annehmen soll. Bei einfachen Workstations wird man hier den Vorgabewert localhost belassen. Wollen wir einen richtigen Mailserver betreiben, so definieren wir hier entweder direkt sine IP-Adresse, oder geben das Schlüsselwort all für alle Netzwerkschnittstellen an.
  • inet_protocols
    Festlegung des verwendeten Internetprotokolles, abhängig von der Serverkonfiguration selbst. Wurde der IPv6-Support deaktiviert, so definiert man hier entsprechend die Option inet_protocols = ipv4.
  • smtpd_banner
    Definition des Begrüßungstextes, den der Mailserver nach dem Aufbau eingehender Verbindungenvon externen Mailservern ausgibt. Hier wird man i.d.R. aus Sicherheitsgründen lediglich den Hostnamen und den Namen des Mailservers preis geben, nicht aber Versionsangaben oder weiteres.

Neben den beiden vorgenannten Hauptkonfigurationsdateien main.cf und master.cf finden wir im Konfigurationsverzeichnis /etc/postfix noch ein paar Lockup-Tabellen, die bei der RPM-Installation automatisch angelegt wurden.

 # # ls -l --hide=*.cf --hide=header_checks --hide=*proto /etc/postfix/
total 112
-rw-r--r--. 1 root root 21006 Sep 24 19:22 access
-rw-r--r--. 1 root root 11683 Sep 24 19:22 canonical
-rw-r--r--. 1 root root  9904 Sep 24 19:22 generic
-rw-r--r--. 1 root root  6816 Sep 24 19:22 relocated
-rw-r--r--. 1 root root 12549 Sep 24 19:22 transport
-rw-r--r--. 1 root root 12510 Sep 24 19:22 virtual

Ferner findet sich dort noch die Konfigurationsdatei dynamicmaps.cf und das zugehörige Verzeichnis dynamicmaps.cf.d für die dynamischen Mappingtabellen.

-rw-r--r--. 1 root root 164 Jan 17 17:09 dynamicmaps.cf
drwxr-xr-x. 2 root root     6 Jan 17 17:09 dynamicmaps.cf.d

Den Umgang mit diesen access- und lookup-Tabellen ist im Kapitel Konfiguration unseres MTAs Postfix 2.11 unter CentOS7 detailliert beschrieben.

Möchte man Informationen im Mailheader zum Bewerten verwenden, um so z.B. eine Nachricht zu blocken, kann man dies mit Hilfe der Konfigurationsdatei header_checks realisieren.

 # less /etc/postfix/header_checks
/etc/postfix/header_checks
# HEADER_CHECKS(5)                                              HEADER_CHECKS(5)
# 
# NAME
#        header_checks - Postfix built-in content inspection
# 
# SYNOPSIS
#        header_checks = pcre:/etc/postfix/header_checks
#        mime_header_checks = pcre:/etc/postfix/mime_header_checks
#        nested_header_checks = pcre:/etc/postfix/nested_header_checks
#        body_checks = pcre:/etc/postfix/body_checks
# 
#        milter_header_checks = pcre:/etc/postfix/milter_header_checks
# 
#        smtp_header_checks = pcre:/etc/postfix/smtp_header_checks
#        smtp_mime_header_checks = pcre:/etc/postfix/smtp_mime_header_checks
#        smtp_nested_header_checks = pcre:/etc/postfix/smtp_nested_header_checks
#        smtp_body_checks = pcre:/etc/postfix/smtp_body_checks
# 
#        postmap -q "string" pcre:/etc/postfix/filename
#        postmap -q - pcre:/etc/postfix/filename <inputfile
# 
# DESCRIPTION
#        This  document  describes access control on the content of
#        message headers and message body lines; it is  implemented
#        by  the  Postfix  cleanup(8) server before mail is queued.
#        See access(5) for access control  on  remote  SMTP  client
#        information.
# 
#        Each  message  header  or  message  body  line is compared
#        against a list of patterns.  When a  match  is  found  the
#        corresponding action is executed, and the matching process
#        is repeated for the next message header  or  message  body
#        line.
# 
#        Note: message headers are examined one logical header at a
#        time, even when a message  header  spans  multiple  lines.
#        Body lines are always examined one line at a time.
# 
#        For  examples, see the EXAMPLES section at the end of this
#        manual page.
# 
#        Postfix header or body_checks are designed to stop a flood
#        of  mail from worms or viruses; they do not decode attach-
#        ments, and they do not unzip archives. See  the  documents
#        referenced  below  in the README FILES section if you need
#        more sophisticated content analysis.
# 
# FILTERS WHILE RECEIVING MAIL
#        Postfix implements the  following  four  built-in  content
#        inspection classes while receiving mail:
# 
#        header_checks (default: empty)
#               These   are  applied  to  initial  message  headers
#               (except for the headers  that  are  processed  with
#               mime_header_checks).
# 
#        mime_header_checks (default: $header_checks)
#               These  are  applied to MIME related message headers
#               only.
# 
#               This feature is available in Postfix 2.0 and later.
# 
#        nested_header_checks (default: $header_checks)
#               These  are  applied  to message headers of attached
#               email messages (except for  the  headers  that  are
#               processed with mime_header_checks).
# 
#               This feature is available in Postfix 2.0 and later.
# 
#        body_checks
#               These are applied to all other  content,  including
#               multi-part message boundaries.
# 
#               With Postfix versions before 2.0, all content after
#               the initial message headers is treated as body con-
#               tent.
# 
# FILTERS AFTER RECEIVING MAIL
#        Postfix  supports a subset of the built-in content inspec-
#        tion classes after the message is received:
# 
#        milter_header_checks (default: empty)
#               These are applied to headers that  are  added  with
#               Milter applications.
# 
#               This feature is available in Postfix 2.7 and later.
# 
# FILTERS WHILE DELIVERING MAIL
#        Postfix supports all four content inspection classes while
#        delivering mail via SMTP.
# 
#        smtp_header_checks (default: empty)
# 
#        smtp_mime_header_checks (default: empty)
# 
#        smtp_nested_header_checks (default: empty)
# 
#        smtp_body_checks (default: empty)
#               These  features  are  available  in Postfix 2.5 and
#               later.
# 
# COMPATIBILITY
#        With Postfix version 2.2 and earlier specify "postmap -fq"
#        to query a table that contains case sensitive patterns. By
#        default, regexp: and pcre: patterns are case  insensitive.
# 
# TABLE FORMAT
#        This  document  assumes  that header and body_checks rules
#        are specified in the form of  Postfix  regular  expression
#        lookup  tables.  Usually  the best performance is obtained
#        with pcre (Perl Compatible Regular Expression) tables. The
#        regexp  (POSIX  regular  expressions)  tables  are usually
#        slower, but more widely available.  Use the command "post-
#        conf  -m" to find out what lookup table types your Postfix
#        system supports.
# 
#        The general format of Postfix regular expression tables is
#        given  below.   For  a  discussion  of specific pattern or
#        flags  syntax,  see  pcre_table(5)   or   regexp_table(5),
#        respectively.
# 
#        /pattern/flags action
#               When  /pattern/  matches  the input string, execute
#               the corresponding action. See below for a  list  of
#               possible actions.
# 
#        !/pattern/flags action
#               When  /pattern/  does  not  match the input string,
#               execute the corresponding action.
# 
#        if /pattern/flags
# 
#        endif  If the input string matches /pattern/,  then  match
#               that  input  string against the patterns between if
#               and endif.  The if..endif can nest.
# 
#               Note: do not prepend whitespace to patterns  inside
#               if..endif.
# 
#        if !/pattern/flags
# 
#        endif  If  the input string does not match /pattern/, then
#               match  that  input  string  against  the   patterns
#               between if and endif. The if..endif can nest.
# 
#        blank lines and comments
#               Empty  lines and whitespace-only lines are ignored,
#               as are lines whose first  non-whitespace  character
#               is a `#'.
# 
#        multi-line text
#               A  pattern/action  line  starts with non-whitespace
#               text. A line that starts with whitespace  continues
#               a logical line.
# 
# TABLE SEARCH ORDER
#        For  each  line of message input, the patterns are applied
#        in the order as specified in the table. When a pattern  is
#        found  that  matches  the  input  line,  the corresponding
#        action is  executed  and  then  the  next  input  line  is
#        inspected.
# 
# TEXT SUBSTITUTION
#        Substitution  of  substrings  from  the matched expression
#        into the action string is possible using the  conventional
#        Perl  syntax  ($1,  $2,  etc.).   The macros in the result
#        string may need to be written as  ${n}  or  $(n)  if  they
#        aren't followed by whitespace.
# 
#        Note:  since negated patterns (those preceded by !) return
#        a result when the expression does not match, substitutions
#        are not available for negated patterns.
# 
# ACTIONS
#        Action names are case insensitive. They are shown in upper
#        case for consistency with other Postfix documentation.
# 
#        BCC user@domain
#               Add the specified address as a BCC  recipient,  and
#               inspect  the next input line. The address must have
#               a local part and domain part.  The  number  of  BCC
#               addresses  that can be added is limited only by the
#               amount of available storage space.
# 
#               Note 1: the BCC address is added as if it was spec-
#               ified  with  NOTIFY=NONE.  The  sender  will not be
#               notified when the BCC address is undeliverable,  as
#               long  as  all  down-stream  software implements RFC
#               3461.
# 
#               Note 2: this ignores duplicate addresses (with  the
#               same delivery status notification options).
# 
#               This feature is available in Postfix 3.0 and later.
# 
#               This feature is not supported with smtp header/body
#               checks.
# 
#        DISCARD optional text...
#               Claim  successful delivery and silently discard the
#               message.  Do not inspect the remainder of the input
#               message.   Log the optional text if specified, oth-
#               erwise log a generic message.
# 
#               Note:  this  action  disables  further  header   or
#               body_checks  inspection  of the current message and
#               affects all recipients.  To discard only one recip-
#               ient without discarding the entire message, use the
#               transport(5) table to direct mail to the discard(8)
#               service.
# 
#               This feature is available in Postfix 2.0 and later.
# 
#               This feature is not supported with smtp header/body
#               checks.
# 
#        DUNNO  Pretend  that the input line did not match any pat-
#               tern, and inspect the next input line. This  action
#               can be used to shorten the table search.
# 
#               For  backwards  compatibility reasons, Postfix also
#               accepts OK but it is (and always has been)  treated
#               as DUNNO.
# 
#               This feature is available in Postfix 2.1 and later.
# 
#        FILTER transport:destination
#               Override the content_filter parameter setting,  and
#               inspect  the next input line.  After the message is
#               queued, send the entire message through the  speci-
#               fied  external  content  filter. The transport name
#               specifies the first field of a mail delivery  agent
#               definition in master.cf; the syntax of the next-hop
#               destination is described in the manual page of  the
#               corresponding  delivery  agent.   More  information
#               about external content filters is  in  the  Postfix
#               FILTER_README file.
# 
#               Note  1: do not use $number regular expression sub-
#               stitutions for transport or destination unless  you
#               know that the information has a trusted origin.
# 
#               Note  2:  this  action  overrides  the main.cf con-
#               tent_filter setting, and affects all recipients  of
#               the  message.  In  the  case  that  multiple FILTER
#               actions fire, only the last one is executed.
# 
#               Note 3: the purpose of the  FILTER  command  is  to
#               override  message routing.  To override the recipi-
#               ent's transport but not the  next-hop  destination,
#               specify  an  empty  filter destination (Postfix 2.7
#               and later), or specify a transport:destination that
#               delivers   through  a  different  Postfix  instance
#               (Postfix 2.6 and earlier). Other options are  using
#               the  recipient-dependent transport_maps or the sen-
#               der-dependent   sender_dependent_default_transport-
#               _maps features.
# 
#               This feature is available in Postfix 2.0 and later.
# 
#               This feature is not supported with smtp header/body
#               checks.
# 
#        HOLD optional text...
#               Arrange  for  the  message to be placed on the hold
#               queue, and inspect the next input line.   The  mes-
#               sage  remains  on hold until someone either deletes
#               it or releases it for delivery.  Log  the  optional
#               text if specified, otherwise log a generic message.
# 
#               Mail that is placed on hold can  be  examined  with
#               the  postcat(1)  command,  and  can be destroyed or
#               released with the postsuper(1) command.
# 
#               Note: use "postsuper -r" to release mail  that  was
#               kept  on  hold for a significant fraction of $maxi-
#               mal_queue_lifetime  or  $bounce_queue_lifetime,  or
#               longer.  Use "postsuper -H" only for mail that will
#               not expire within a few delivery attempts.
# 
#               Note: this action affects  all  recipients  of  the
#               message.
# 
#               This feature is available in Postfix 2.0 and later.
# 
#               This feature is not supported with smtp header/body
#               checks.
# 
#        IGNORE Delete the current line from the input, and inspect
#               the next input line. See STRIP for  an  alternative
#               that logs the action.
# 
#        INFO optional text...
#               Log an "info:" record with the optional text... (or
#               log a generic text), and  inspect  the  next  input
#               line.  This action is useful for routine logging or
#               for debugging.
# 
#               This feature is available in Postfix 2.8 and later.
# 
#        PASS optional text...
#               Log  a "pass:" record with the optional text... (or
#               log a generic text), and turn off header, body, and
#               Milter  inspection  for  the remainder of this mes-
#               sage.
# 
#               Note: this feature relies on trust  in  information
#               that is easy to forge.
# 
#               This feature is available in Postfix 3.2 and later.
# 
#               This feature is not supported with smtp header/body
#               checks.
# 
#        PREPEND text...
#               Prepend  one  line  with  the  specified  text, and
#               inspect the next input line.
# 
#               Notes:
# 
#               o      The prepended text is output on  a  separate
#                      line,  immediately  before  the  input  that
#                      triggered the PREPEND action.
# 
#               o      The prepended text is not considered part of
#                      the  input  stream:  it  is  not  subject to
#                      header/body checks or address rewriting, and
#                      it does not affect the way that Postfix adds
#                      missing message headers.
# 
#               o      When prepending text before a message header
#                      line,  the  prepended text must begin with a
#                      valid message header label.
# 
#               o      This  action  cannot  be  used  to   prepend
#                      multi-line text.
# 
#               This feature is available in Postfix 2.1 and later.
# 
#               This   feature   is   not   supported   with   mil-
#               ter_header_checks.
# 
#        REDIRECT user@domain
#               Write  a  message  redirection request to the queue
#               file, and inspect the next input  line.  After  the
#               message is queued, it will be sent to the specified
#               address instead of the intended recipient(s).
# 
#               Note: this action overrides the FILTER action,  and
#               affects  all recipients of the message. If multiple
#               REDIRECT actions fire, only the last  one  is  exe-
#               cuted.
# 
#               This feature is available in Postfix 2.1 and later.
# 
#               This feature is not supported with smtp header/body
#               checks.
# 
#        REPLACE text...
#               Replace  the  current line with the specified text,
#               and inspect the next input line.
# 
#               This feature is available in Postfix 2.2 and later.
#               The  description below applies to Postfix 2.2.2 and
#               later.
# 
#               Notes:
# 
#               o      When replacing a message  header  line,  the
#                      replacement  text  must  begin  with a valid
#                      header label.
# 
#               o      The replaced text remains part of the  input
#                      stream.  Unlike  the result from the PREPEND
#                      action, a replaced  message  header  may  be
#                      subject  to address rewriting and may affect
#                      the way that Postfix  adds  missing  message
#                      headers.
# 
#        REJECT optional text...
#               Reject  the  entire  message.  Do  not  inspect the
#               remainder  of  the  input  message.    Reply   with
#               optional  text...  when the optional text is speci-
#               fied, otherwise reply with a generic error message.
# 
#               Note:   this  action  disables  further  header  or
#               body_checks inspection of the current  message  and
#               affects all recipients.
# 
#               Postfix version 2.3 and later support enhanced sta-
#               tus codes.  When no code is specified at the begin-
#               ning of optional text..., Postfix inserts a default
#               enhanced status code of "5.7.1".
# 
#               This feature is not supported with smtp header/body
#               checks.
# 
#        STRIP optional text...
#               Log a "strip:" record with the optional text... (or
#               log a generic text), delete the input line from the
#               input,  and inspect the next input line. See IGNORE
#               for a silent alternative.
# 
#               This feature is available in Postfix 3.2 and later.
# 
#        WARN optional text...
#               Log  a  "warning:" record with the optional text...
#               (or log a generic text), and inspect the next input
#               line.  This  action is useful for debugging and for
#               testing a  pattern  before  applying  more  drastic
#               actions.
# 
# BUGS
#        Empty lines never match, because some map types mis-behave
#        when given a zero-length search string.   This  limitation
#        may  be  removed for regular expression tables in a future
#        release.
# 
#        Many people overlook the main limitations  of  header  and
#        body_checks rules.
# 
#        o      These  rules  operate on one logical message header
#               or one body line at a time. A decision made for one
#               line is not carried over to the next line.
# 
#        o      If  text  in the message body is encoded (RFC 2045)
#               then the rules need to be specified for the encoded
#               form.
# 
#        o      Likewise,  when  message  headers  are encoded (RFC
#               2047) then the rules need to be specified  for  the
#               encoded form.
# 
#        Message  headers added by the cleanup(8) daemon itself are
#        excluded from inspection. Examples of such message headers
#        are From:, To:, Message-ID:, Date:.
# 
#        Message  headers  deleted by the cleanup(8) daemon will be
#        examined before they are deleted. Examples are: Bcc:, Con-
#        tent-Length:, Return-Path:.
# 
# CONFIGURATION PARAMETERS
#        body_checks
#               Lookup tables with content filter rules for message
#               body lines.  These filters see one physical line at
#               a  time,  in  chunks  of at most $line_length_limit
#               bytes.
# 
#        body_checks_size_limit
#               The amount of  content  per  message  body  segment
#               (attachment) that is subjected to $body_checks fil-
#               tering.
# 
#        header_checks
# 
#        mime_header_checks (default: $header_checks)
# 
#        nested_header_checks (default: $header_checks)
#               Lookup tables with content filter rules for message
#               header  lines:  respectively,  these are applied to
#               the initial message  headers  (not  including  MIME
#               headers),  to the MIME headers anywhere in the mes-
#               sage, and to the initial headers of  attached  mes-
#               sages.
# 
#               Note:  these filters see one logical message header
#               at a time, even when a message header spans  multi-
#               ple  lines.  Message  headers  that are longer than
#               $header_size_limit characters are truncated.
# 
#        disable_mime_input_processing
#               While receiving mail, give no special treatment  to
#               MIME  related  message  headers; all text after the
#               initial message headers is considered to be part of
#               the  message body. This means that header_checks is
#               applied to all the  initial  message  headers,  and
#               that body_checks is applied to the remainder of the
#               message.
# 
#               Note: when used in this  manner,  body_checks  will
#               process  a  multi-line message header one line at a
#               time.
# 
# EXAMPLES
#        Header pattern to block attachments  with  bad  file  name
#        extensions.   For  convenience, the PCRE /x flag is speci-
#        fied, so that there is no need  to  collapse  the  pattern
#        into   a   single  line  of  text.   The  purpose  of  the
#        [[:xdigit:]] sub-expressions is to recognize Windows CLSID
#        strings.
# 
#        /etc/postfix/main.cf:
#            header_checks = pcre:/etc/postfix/header_checks.pcre
# 
#        /etc/postfix/header_checks.pcre:
#            /^Content-(Disposition|Type).*name\s*=\s*"?([^;]*(\.|=2E)(
#              ade|adp|asp|bas|bat|chm|cmd|com|cpl|crt|dll|exe|
#              hlp|ht[at]|
#              inf|ins|isp|jse?|lnk|md[betw]|ms[cipt]|nws|
#              \{[[:xdigit:]]{8}(?:-[[:xdigit:]]{4}){3}-[[:xdigit:]]{12}\}|
#              ops|pcd|pif|prf|reg|sc[frt]|sh[bsm]|swf|
#              vb[esx]?|vxd|ws[cfh]))(\?=)?"?\s*(;|$)/x
#                REJECT Attachment name "$2" may not end with ".$4"
# 
#        Body pattern to stop a specific HTML browser vulnerability
#        exploit.
# 
#        /etc/postfix/main.cf:
#            body_checks = regexp:/etc/postfix/body_checks
# 
#        /etc/postfix/body_checks:
#            /^<iframe src=(3D)?cid:.* height=(3D)?0 width=(3D)?0>$/
#                REJECT IFRAME vulnerability exploit
# 
# SEE ALSO
#        cleanup(8), canonicalize and enqueue Postfix message
#        pcre_table(5), format of PCRE lookup tables
#        regexp_table(5), format of POSIX regular expression tables
#        postconf(1), Postfix configuration utility
#        postmap(1), Postfix lookup table management
#        postsuper(1), Postfix janitor
#        postcat(1), show Postfix queue file contents
#        RFC 2045, base64 and quoted-printable encoding rules
#        RFC 2047, message header encoding for non-ASCII text
# 
# README FILES
#        Use "postconf readme_directory" or  "postconf  html_direc-
#        tory" to locate this information.
#        DATABASE_README, Postfix lookup table overview
#        CONTENT_INSPECTION_README, Postfix content inspection overview
#        BUILTIN_FILTER_README, Postfix built-in content inspection
#        BACKSCATTER_README, blocking returned forged mail
# 
# LICENSE
#        The  Secure  Mailer  license must be distributed with this
#        software.
# 
# AUTHOR(S)
#        Wietse Venema
#        IBM T.J. Watson Research
#        P.O. Box 704
#        Yorktown Heights, NY 10598, USA
# 
#        Wietse Venema
#        Google, Inc.
#        111 8th Avenue
#        New York, NY 10011, USA
# 
#                                                               HEADER_CHECKS(5)

Wie dies im Detail von Statten geht werden wir uns in einem separaten Schritt Grundabsicherung von Postfix noch genauer ansehen.

Damit fremde MTAs2) auf SMTP-Port 25 und unsere Kunden mit deren MUAs3) auf dem Submission-Port 587 ihre Nachrichten bei unserem Postfix-Mailserver einliefern können, müssen wir für diese noch Änderungen am Paketfilter firewalld vornehmen.

 # firewall-cmd --permanent --zone=public --add-port=25/tcp
 success
 # firewall-cmd --permanent --zone=public --add-port=587/tcp
 success

Anschließend können wir den Firewall-Daemon einmal durchstarten und anschließend überprüfen, ob die Regeln auch entsprechend unserer Definition, gezogen haben.

 # firewall-cmd --reload
 success

Abschließend prüfen wir noch, ob die Erweiterung unseres Paketfilter aktiv ist.

 # iptables -nvL IN_public_allow
Chain IN_public_allow (1 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:22 ctstate NEW
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:25 ctstate NEW
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:587 ctstate NEW

erster manueller Start

 # systemctl start postfix.service

Im Maillog wird der Start unseres Postfix-Servers entsprechend vermerkt.

 # less /var/log/maillog
Oct 10 22:41:25 vml000087.dmz.nausch.org systemd[1]: Starting Postfix Mail Transport Agent...
Oct 10 22:41:26 vml000087.dmz.nausch.org postfix/master[30590]: daemon started -- version 2.11.1, configuration /etc/postfix
Oct 10 22:41:26 vml000087.dmz.nausch.org systemd[1]: Started Postfix Mail Transport Agent.
 # systemctl status postfix.service

postfix.service - Postfix Mail Transport Agent
   Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled; vendor preset: disabled)
   Active: active (running) since Sat 2019-01-26 21:41:21 CET; 12s ago
  Process: 14349 ExecStart=/usr/sbin/postfix start (code=exited, status=0/SUCCESS)
  Process: 14346 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)
  Process: 14341 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=0/SUCCESS)
 Main PID: 14423 (master)
   CGroup: /system.slice/postfix.service
           ├─14423 /usr/libexec/postfix/master -w
           ├─14424 pickup -l -t unix -u
           └─14425 qmgr -l -t unix -u

Jan 26 21:41:20 vml000080.dmz.nausch.org systemd[1]: Starting Postfix Mail Transport Agent...
Jan 26 21:41:21 vml000080.dmz.nausch.org postfix/postfix-script[14421]: starting the Postfix mail system
Jan 26 21:41:21 vml000080.dmz.nausch.org postfix/master[14423]: daemon started -- version 3.3.2, configuration /etc/postfix
Jan 26 21:41:21 vml000080.dmz.nausch.org systemd[1]: Started Postfix Mail Transport Agent.

Fragen wir nun mit Hilfe des Befehls netstat -tulpen die offenen Ports ab, sehen wir, dass der Port 25 auf beiden zur Verfügung stehenden Netzwerkinterfaces geöffnet wurden.

 # netstat -tulpen
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       User       Inode      PID/Program name    
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      0          48472      14423/master        
tcp6       0      0 ::1:25                  :::*                    LISTEN      0          48473      14423/master

Alternativ dazu können wr auch den Befehl lsof verwenden.

 # lsof -i :25
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
master  14423 root   13u  IPv4  48472      0t0  TCP localhost:smtp (LISTEN)
master  14423 root   14u  IPv6  48473      0t0  TCP localhost:smtp (LISTEN)

automatischer Start beim Systemstart

Wollen wir den Daemon beim Hochfahren des Systems automatisch starten, greifen wir auf den Befehl systemctl zurück.

 # systemctl enable postfix.service

Möchten wir uns vergewissern, ob der Daemon beim Systemstart gestartet wird oder nicht, erfahren wir ebenfalls mit dem Befehl systemctl.

 # systemctl is-enabled postfix.service
 enabled

Startet der Server nicht automatisch, wird uns ein „disabled“ zurückgemeldet.

Mit der minimalen Konfiguration unseres Postfix haben wir bereits einen lauffähigen MTA. Zum Testen verwenden wir das Programm telnet. Die Eingaben am testenden Client sind in der Farbe blau und die Rückmeldungen unseres Dovecot-Servers in der Farbe hellgrau gekennzeichnet. Die Ausgaben des Befehls telnet sind in der Farbe schwarz eingefärbt.

$ telnet ::1 25
Trying ::1...
Connected to ::1.
Escape character is '^]'.
220 vml000087.dmz.nausch.org ESMTP Postfix
helo foo
250 vml000087.dmz.nausch.org
mail from:<>
250 2.1.0 OK
rcpt to:<django@vml000080.dmz.nausch.org>>
250 2.1.0 OK
DATA
354 End data with <CR><LF>.<CR><LF>
From: michael@nausch.org
To: django@vml000087.dmz.nausch.org
Subject: erste testmail
Date: heute

test
.
250 2.0.0 Ok: queued as 5FFA5600088
quit
221 2.0.0 Bye
Connection closed by foreign host.

Die Message-ID 5FFA5600088 finden wir dann auch im Maillog wieder.

 # tail -n7 /var/log/maillog 
Jan 26 22:03:03 vml000080.dmz.nausch.org postfix/smtpd[14470]: connect from localhost[::1]
Jan 26 22:03:46 vml000080.dmz.nausch.org postfix/smtpd[14470]: 5FFA5600088: client=localhost[::1]
Jan 26 22:04:20 vml000080.dmz.nausch.org postfix/cleanup[14474]: 5FFA5600088: message-id=<20190126210346.5FFA5600088@vml000080.dmz.nausch.org>
Jan 26 22:04:20 vml000080.dmz.nausch.org postfix/qmgr[14425]: 5FFA5600088: from=<>, size=363, nrcpt=1 (queue active)
Jan 26 22:04:20 vml000080.dmz.nausch.org postfix/local[14475]: 5FFA5600088: to=<django@vml000080.dmz.nausch.org>, relay=local, delay=61, delays=60/0.02/0/0, dsn=2.0.0, status=sent (delivered to mailbox)
Jan 26 22:04:20 vml000080.dmz.nausch.org postfix/qmgr[14425]: 5FFA5600088: removed
Jan 26 22:04:23 vml000080.dmz.nausch.org postfix/smtpd[14470]: disconnect from localhost[::1] helo=1 mail=1 rcpt=1 data=1 quit=1 commands=5

Auf unserem Festplatten wurde die eMail auch entsprechend abgespeichert.

/var/spool/mail/
├── django
└── root
 # cat /var/spool/mail/django
From MAILER-DAEMON  Sat Jan 26 22:04:20 2019
Return-Path: <>
X-Original-To: django@vml000080.dmz.nausch.org
Delivered-To: django@vml000080.dmz.nausch.org
Received: from foo (localhost [IPv6:::1])
	by vml000080.dmz.nausch.org (Postfix) with SMTP id 5FFA5600088
	for <django@vml000080.dmz.nausch.org>; Sat, 26 Jan 2019 22:03:19 +0100 (CET)
From: michael@nausch.org
To: django@vml000087.dmz.nausch.org
Subject: erste testmail
Date: heute
Message-Id: <20190126210346.5FFA5600088@vml000080.dmz.nausch.org>

test

Links


1) , 2)
Mail Transfer Agent
3)
Mail User Agent
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