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

env.sample

@@ -1,8 +1,111 @@
+# ============================================
+# Postfix SMTP Relay - Environment Variables
+# ============================================
+# Copy this file to .env and configure your settings
+# Supports: Maileroo, Mailtrap, SendGrid, and generic SMTP servers
+
+# ============================================
+# General Configuration
+# ============================================
+
+# Timezone (default: America/New_York)
 TIMEZONE='America/New_York'
-SMTP_SERVER='smtp.example.com'
-SERVER_HOSTNAME=server_name
+
+# Domain for outgoing mail
+DOMAIN=example.com
+
+# Server hostname (optional - defaults to container hostname)
+SERVER_HOSTNAME=mail.example.com
+
+# Port to expose on host (default: 25)
+SMTP_LISTEN_PORT=25
+
+# Data folder for logs, mail, and spool (default: current directory)
+DATA_FOLDER=./data
+
+# Optional: Custom networks to allow relay (comma-separated CIDR notation)
+# SMTP_NETWORKS=192.168.1.0/24,10.0.0.0/8
+
+# Optional: Add custom header tag to relayed messages
+# SMTP_HEADER_TAG=MyRelay
+
+# Debug mode (yes/no) - enables verbose logging
+DEBUG=no
+
+# ============================================
+# SMTP Provider Configuration
+# Choose ONE of the following configurations
+# ============================================
+
+# --------------------------------------------
+# Option 1: Maileroo (Current Configuration)
+# --------------------------------------------
+SMTP_SERVER='smtp.maileroo.com'
 SMTP_PORT=587
-DOMAIN=smtp_domain
-SMTP_USERNAME=apikey
-SMTP_PASSWORD='api_key'
-DATA_FOLDER='Local data folder'
+SMTP_USERNAME=noreply@example.com
+SMTP_PASSWORD=your_maileroo_password_here
+
+# --------------------------------------------
+# Option 2: Mailtrap
+# --------------------------------------------
+# SMTP_SERVER='live.smtp.mailtrap.io'
+# SMTP_PORT=587
+# SMTP_USERNAME=your_mailtrap_username
+# SMTP_PASSWORD=your_mailtrap_password
+
+# For Mailtrap Sandbox (testing):
+# SMTP_SERVER='sandbox.smtp.mailtrap.io'
+# SMTP_PORT=2525
+# SMTP_USERNAME=your_mailtrap_sandbox_username
+# SMTP_PASSWORD=your_mailtrap_sandbox_password
+
+# --------------------------------------------
+# Option 3: SendGrid
+# --------------------------------------------
+# SMTP_SERVER='smtp.sendgrid.net'
+# SMTP_PORT=587
+# SMTP_USERNAME=apikey
+# SMTP_PASSWORD=your_sendgrid_api_key_here
+
+# --------------------------------------------
+# Option 4: Generic SMTP Server
+# --------------------------------------------
+# SMTP_SERVER='smtp.example.com'
+# SMTP_PORT=587
+# SMTP_USERNAME=your_username
+# SMTP_PASSWORD=your_password
+
+# --------------------------------------------
+# Option 5: Gmail (requires app password)
+# --------------------------------------------
+# SMTP_SERVER='smtp.gmail.com'
+# SMTP_PORT=587
+# SMTP_USERNAME=your_email@gmail.com
+# SMTP_PASSWORD=your_app_password
+
+# --------------------------------------------
+# Option 6: Office 365 / Outlook
+# --------------------------------------------
+# SMTP_SERVER='smtp.office365.com'
+# SMTP_PORT=587
+# SMTP_USERNAME=your_email@outlook.com
+# SMTP_PASSWORD=your_password
+
+# ============================================
+# Notes
+# ============================================
+#
+# 1. The container automatically detects /16 subnet for relay
+#    Additional networks can be added via SMTP_NETWORKS
+#
+# 2. All logs are sent to stderr and visible via:
+#    docker logs postfix-relay
+#
+# 3. TLS is automatically enabled for known providers
+#    (Maileroo, Mailtrap, SendGrid)
+#
+# 4. Health check monitors Postfix status every 30 seconds
+#
+# 5. For SendGrid, username must be "apikey" (literal string)
+#
+# ============================================