feat: self-hosted postfix

docker/postfix/Dockerfile

@@ -0,0 +1,30 @@
+FROM debian:bookworm-slim
+
+# install oostfix and OpenDKIM
+RUN apt-get update && apt-get install -y \
+    postfix \
+    opendkim \
+    opendkim-tools \
+    mailutils \
+    ca-certificates \
+    netcat-openbsd \
+    && rm -rf /var/lib/apt/lists/*
+
+# create OpenDKIM paths
+RUN mkdir -p /etc/opendkim/keys && \
+    chown -R opendkim:opendkim /etc/opendkim && \
+    chmod 700 /etc/opendkim/keys
+
+# copy config
+COPY postfix-main.cf /etc/postfix/main.cf
+COPY opendkim.conf /etc/opendkim.conf
+COPY entrypoint.sh /entrypoint.sh
+
+RUN chmod +x /entrypoint.sh
+
+EXPOSE 25
+
+HEALTHCHECK --interval=30s --timeout=10s --start-period=10s --retries=3 \
+    CMD echo "QUIT" | nc -w 5 localhost 25 | grep -q "220" || exit 1
+
+ENTRYPOINT ["/entrypoint.sh"]