add virtual aliases

README.md

@@ -287,6 +287,14 @@ The format of this file is as-per the [`/etc/aliases`](https://linux.die.net/man
 
 The system aliases file maps `postmaster`, `root`, `postfix` and `clamav` through to the address specified by `POSTMASTER_EMAIL`.
 
+### Virtual Aliases
+
+The format of this file is as-per the [`/etc/postfix/virtual`](https://www.postfix.org/VIRTUAL_README.html#virtual_alias) file.
+
+| Configuration file (with respect to container) | If this file is present... | After modifying... |
+|-----|-----|-----|
+| `/etc/postfix/tables/virtual` | It is created with the defined content. | Run helper command `postconf` (see below). |
+
 ## Paths
 
 ### Required to be mapped

rootfs/etc/cont-init.d/10-postfix-generate-main.cf.sh

@@ -20,6 +20,11 @@ CHECK_RECIPIENT_ACCESS=""
   # http://www.postfix.org/postconf.5.html#alias_maps
   echo "alias_maps = hash:/etc/aliases"
 
+  # https://www.postfix.org/postconf.5.html#virtual_alias_maps
+  if [ -f "/etc/postfix/tables/virtual" ]; then
+    echo "virtual_alias_maps = hash:/etc/postfix/virtual"
+  fi
+
   # http://www.postfix.org/SMTPUTF8_README.html
   if [ "${POSTFIX_SMTPUTF8_ENABLE}" = "true" ]; then
     echo "smtputf8_enable = yes"

rootfs/usr/local/bin/update_virtual_aliases

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# shellcheck shell=bash
+
+VIRTUAL_ALIASES_FILE="/etc/postfix/virtual"
+VIRTUAL_ALIASES_FILE_LOCAL="/etc/postfix/tables/virtual"
+
+if [ -f "${VIRTUAL_ALIASES_FILE_LOCAL}" ]; then
+    cat "${VIRTUAL_ALIASES_FILE_LOCAL}" > "${VIRTUAL_ALIASES_FILE}"
+    postmap "${VIRTUAL_ALIASES_FILE}"
+fi