Initial commit: Postfix mail server with SES relay

- Containerized Postfix configuration for mailing list management
- Environment-based configuration for SES credentials
- Template-based config generation for flexibility
- Static virtual aliases (Phase 1)
- Prepared for future web interface and SQL backend (Phase 2+)

Features:
- Docker Compose orchestration
- Secure credential management via .env
- Configurable SMTP host/port
- Git-ignored sensitive files
- Comprehensive documentation

postfix/Dockerfile

@@ -0,0 +1,25 @@
+FROM debian:stable-slim
+
+# Install Postfix and tools
+RUN apt-get update && \
+    DEBIAN_FRONTEND=noninteractive apt-get install -y \
+        postfix \
+        libsasl2-modules \
+        mailutils \
+        gettext-base \
+        && apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# Copy configs
+COPY main.cf.template /etc/postfix/main.cf.template
+COPY sasl_passwd.template /etc/postfix/sasl_passwd.template
+COPY virtual_aliases.cf /etc/postfix/virtual_aliases.cf
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+# Generate Postfix maps for virtual aliases
+RUN postmap /etc/postfix/virtual_aliases.cf
+
+# Expose SMTP
+EXPOSE 25
+
+ENTRYPOINT ["/entrypoint.sh"]