Adding the configuration change for multiple provider, Making the service run in foreground and adding test

docker-compose.yml

@@ -1,19 +1,48 @@
+version: "3.8"
+
 services:
   postfix:
-    container_name: postfix
-    image: docker.io/k2patel/postfix:latest
-    ports:
-      - "10825:25/tcp"
-    environment:
-      TIMEZONE: ${TIMEZONE}
-      SMTP_SERVER: ${SMTP_SERVER}
-      SERVER_HOSTNAME: ${SERVER_HOSTNAME}
-      SMTP_PORT: ${SMTP_PORT}
-      DOMAIN: ${DOMAIN}
-      SMTP_USERNAME: ${SMTP_USERNAME}
-      SMTP_PASSWORD: ${SMTP_PASSWORD}
-    volumes:
-      - "${DATA_FOLDER}/logs:/var/log"
-      - "${DATA_FOLDER}/mail:/var/mail"
-      - "${DATA_FOLDER}/spool:/var/spool/postfix"
+    build: .
+    container_name: postfix-relay
+    hostname: ${SERVER_HOSTNAME:-postfix-relay}
     restart: unless-stopped
+    ports:
+      - "${SMTP_LISTEN_PORT:-25}:25"
+    environment:
+      - TIMEZONE=${TIMEZONE:-America/New_York}
+      - SMTP_SERVER=${SMTP_SERVER}
+      - SMTP_PORT=${SMTP_PORT:-587}
+      - SMTP_USERNAME=${SMTP_USERNAME}
+      - SMTP_PASSWORD=${SMTP_PASSWORD}
+      - DOMAIN=${DOMAIN}
+      - SERVER_HOSTNAME=${SERVER_HOSTNAME}
+      - SMTP_NETWORKS=${SMTP_NETWORKS}
+      - SMTP_HEADER_TAG=${SMTP_HEADER_TAG}
+      - DEBUG=${DEBUG:-no}
+    volumes:
+      - "${DATA_FOLDER:-.}/logs:/var/log"
+      - "${DATA_FOLDER:-.}/mail:/var/mail"
+      - "${DATA_FOLDER:-.}/spool:/var/spool/postfix"
+    networks:
+      - postfix-network
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "10m"
+        max-file: "3"
+        labels: "service=postfix-relay"
+    healthcheck:
+      test: ["CMD", "postfix", "status"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 40s
+
+networks:
+  postfix-network:
+    driver: bridge
+    ipam:
+      driver: default
+      config:
+        - subnet: 172.28.0.0/16
+          gateway: 172.28.0.1