add POSTFIX_DSN

Dockerfile

@@ -201,7 +201,7 @@ RUN echo 'Reason_Message = Message {rejectdefer} due to: {spf}.' >>/etc/postfix-
 
 COPY target/fetchmail/fetchmailrc /etc/fetchmailrc_general
 COPY target/getmail/getmailrc /etc/getmailrc_general
-COPY target/postfix/main.cf target/postfix/master.cf /etc/postfix/
+COPY target/postfix/main.cf target/postfix/master.cf target/postfix/esmtp_access /etc/postfix/
 
 # DH parameters for DHE cipher suites, ffdhe4096 is the official standard 4096-bit DH params now part of TLS 1.3
 # This file is for TLS <1.3 handshakes that rely on DHE cipher suites

mailserver.env

@@ -332,6 +332,17 @@ REPORT_SENDER=
 LOGROTATE_INTERVAL=weekly
 
 
+# Choose how Postfix handles DSN (Delivery Status Notification) requests
+# empty => Regardless of its origin, a DSN request is always fulfilled.
+#   1   => It can only be requested by authenticated users.
+#   2   => DSN is completely disabled. (not recommended)
+#
+# Note: If this option is left empty and you are using DMARC (reject, quarantine),
+# add an SPF record for the FQDN, since the email won't be signd with DKIM and will
+# be sent from mail.example.com instead of example.com.
+#
+POSTFIX_DSN=
+
 # If enabled, employs `reject_unknown_client_hostname` to sender restrictions in Postfix's configuration.
 #
 # - **0** => Disabled

target/postfix/esmtp_access

@@ -0,0 +1,2 @@
+0.0.0.0/0   silent-discard, dsn
+::/0        silent-discard, dsn

target/scripts/startup/setup.d/postfix.sh

@@ -57,6 +57,15 @@ EOF
   __postfix__log 'trace' "Configuring virtual mailbox size limit to '${POSTFIX_MAILBOX_SIZE_LIMIT}'"
   postconf "virtual_mailbox_limit = ${POSTFIX_MAILBOX_SIZE_LIMIT}"
 
+  if [[ ${POSTFIX_DSN} -eq 1 ]]; then
+    __postfix__log 'trace' 'Disabling DSN for unauthenticated users'
+    sedfile -i -E '/^submissions?\>/a\  -o smtpd_discard_ehlo_keyword_address_maps=' /etc/postfix/master.cf
+    postconf 'smtpd_discard_ehlo_keyword_address_maps = cidr:/etc/postfix/esmtp_access'
+  elif [[ ${POSTFIX_DSN} -eq 2 ]]; then
+    __postfix__log 'trace' 'Disabling DSN completely'
+    postconf 'smtpd_discard_ehlo_keywords = silent-discard, dsn'
+  fi
+
   if [[ ${POSTFIX_REJECT_UNKNOWN_CLIENT_HOSTNAME} -eq 1 ]]; then
     __postfix__log 'trace' 'Enabling reject_unknown_client_hostname to dms_smtpd_sender_restrictions'
     sedfile -i -E \

target/scripts/startup/variables-stack.sh

@@ -115,6 +115,7 @@ function __environment_variables_general_setup() {
   VARS[DOVECOT_MAILBOX_FORMAT]="${DOVECOT_MAILBOX_FORMAT:=maildir}"
   VARS[DOVECOT_TLS]="${DOVECOT_TLS:=no}"
 
+  VARS[POSTFIX_DSN]="${POSTFIX_DSN:=0}"
   VARS[POSTFIX_DAGENT]="${POSTFIX_DAGENT:=}"
   VARS[POSTFIX_INET_PROTOCOLS]="${POSTFIX_INET_PROTOCOLS:=all}"
   VARS[POSTFIX_MAILBOX_SIZE_LIMIT]="${POSTFIX_MAILBOX_SIZE_LIMIT:=0}"