From 359b1396b2c0ae7fcd9b24013e8c54d850b79c0f 2024-02-28 22:30:32
From: Branko Majic <branko@majic.rs>
Date: 2024-02-28 22:30:32
Subject: [PATCH] MAR-192: Reformat and add comments for the mail_forwarder Postfix configuration file.

---

diff --git a/roles/mail_forwarder/templates/main.cf.j2 b/roles/mail_forwarder/templates/main.cf.j2
index bb0295eeb99018bc53b36219a8fc33d4a4662b53..6201ea6b9c14cbc07965f7cf8a15aeff2e41d54c 100644
--- a/roles/mail_forwarder/templates/main.cf.j2
+++ b/roles/mail_forwarder/templates/main.cf.j2
@@ -1,52 +1,79 @@
 # See /usr/share/postfix/main.cf.dist for a commented, more complete version
 
+# Under Debian, when a file name is specified, the first line of the
+# file be used as the SMTP server's name.
+myorigin = /etc/mailname
 
-# Debian specific:  Specifying a file name will cause the first
-# line of that file to be used as the name.  The Debian default
-# is /etc/mailname.
-#myorigin = /etc/mailname
-
+# Text shown to connecting clients as part of SMTP greeting.
 smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
+
+# Disable the use of local biff service for new mail notifications to
+# local users.
 biff = no
 
-# appending .domain is the MUA's job.
+# Do not append server's domain to locally sent mail. This is up to
+# sending MUAs to take care of.
 append_dot_mydomain = no
 
-# Uncomment the next line to generate "delayed mail" warnings
-#delay_warning_time = 4h
-
+# Disable output of Postfix README file paths when invoking postconf.
 readme_directory = no
 
-# TLS parameters
+# Enable opportunistic TLS. Announce to connecting clients it is
+# enabled, but do not enforce it.
+smtpd_use_tls=yes
+
+# Use locally-issued self-signed certificates for TLS.
 smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
 smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
+
+# Use custom, generated DH parameters for increased security.
 smtpd_tls_dh1024_param_file = /etc/ssl/private/{{ inventory_hostname }}_smtp.dh.pem
 smtpd_tls_dh512_param_file = /etc/ssl/private/{{ inventory_hostname }}_smtp.dh.pem
-smtpd_use_tls=yes
+
+# Enable TLS session cache database for SMTP client. Helps with
+# performance and bandwidth usage.
 smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
+
 {% if smtp_relay_host %}
+# Force full TLS certificate validation for SMTP client when it
+# connect to relay host.
 smtp_tls_security_level=verify
 smtp_tls_CAfile=/etc/ssl/certs/smtp_relay_truststore.pem
 {% endif %}
 
-# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
-# information on enabling SSL in the smtp client.
+# Static relay host to use for outgoing mails from this server.
+relayhost = {{ smtp_relay_host }}{% if smtp_relay_host and smtp_relay_host_port %}:{{ smtp_relay_host_port }}{% endif %}
 
+# Internet hostname of this mail system.
 myhostname = {{ inventory_hostname }}
+
+# Alias maps for local deliveries (to system accounts).
 alias_maps = hash:/etc/aliases
+
+# Alias database that gets updated when invoking "newaliases" command.
 alias_database = hash:/etc/aliases
-myorigin = /etc/mailname
+
+# List of domains for local transport deliveries.
 mydestination = {{ inventory_hostname }}, {{ inventory_hostname_short }}, localhost.localdomain, localhost
-relayhost = {{ smtp_relay_host }}{% if smtp_relay_host and smtp_relay_host_port %}:{{ smtp_relay_host_port }}{% endif %}{{ '' }}
+
+# List of trusted networks allowed to relay mail through this system.x
 mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
+
+# External command for local mail deliveries.
 mailbox_command = procmail -a "$EXTENSION"
+
+# Disable size limits for local user mailboxes.
 mailbox_size_limit = 0
+
+# Recipient delimeter for separating user name from its extension.
 recipient_delimiter = +
+
+# Listen on all network interfaces and all protocols.
 inet_interfaces = all
 inet_protocols = all
 
-# Fall-back to using native lookups (/etc/hosts etc) if DNS lookup fails. Useful
-# for local overrides of mail servers.
+# Fall-back to using native lookups (/etc/hosts etc) if DNS lookup
+# fails. Useful for local overrides of mail servers.
 smtp_host_lookup = dns, native
 
 # Explicitly set maximum allowed mail size that should be accepted.