Add first step at optional mailman configs

.env.sample

@@ -146,3 +146,8 @@ LOG_LEVEL=WARNING
 # Database settings
 ###################################
 DB_FLAVOR=sqlite
+
+###################################
+# Mailman settings
+###################################
+# COMPOSE_FILE="compose.yml:compose.mailman.yml"

compose.mailman.yml

@@ -0,0 +1,12 @@
+version: "3.6"
+
+services:
+  smtp:
+    configs:
+      - source: postfix_override
+        target: /mailu/overrides/postfix.cf
+
+configs:
+  postfix_override:
+    name: ${STACK_NAME}_postfix_overrides_${POSTFIX_OVERRIDE_VERSION}
+    file: postfix.cf.tmpl

postfix.cf.tmpl

@@ -0,0 +1,17 @@
+# https://github.com/maxking/docker-mailman#setting-up-your-mta
+# https://mailu.io/1.7/faq.html?highlight=override#how-can-i-override-settings
+# https://github.com/Mailu/Mailu/blob/master/core/postfix/conf/main.cf
+
+unknown_local_recipient_reject_code = 550
+owner_request_special = no
+
+transport_maps =
+    ${podop}transport
+    regexp:/opt/mailman/core/var/data/postfix_lmtp
+
+local_recipient_maps =
+    regexp:/opt/mailman/core/var/data/postfix_lmtp
+
+relay_domains =
+    ${podop}transport
+    regexp:/opt/mailman/core/var/data/postfix_domains