add docker version

docker/smtp/Dockerfile

@@ -0,0 +1,37 @@
+FROM debian:stable-slim
+# FROM bitnami/minideb:latest
+
+LABEL maintainer="Ludovic CANDELLIER <ludo@huma.net>"
+
+# Set Environment Variables
+ENV DEBIAN_FRONTEND noninteractive
+
+# Start as root
+USER root
+
+# always run apt update when start and after add new source list, then clean up at end.
+RUN apt-get update -yqq; \
+    apt-get upgrade -yqq; \
+    apt-get -yqq install --no-install-recommends apt-utils procps rsyslog apt-transport-https lsb-release ca-certificates curl wget \
+    logrotate postfix
+
+COPY ./conf/main.cf /etc/postfix/main.cf
+
+# RUN ln -snf /etc/services /var/spool/postfix/etc/services
+
+COPY run.sh /
+RUN chmod +x /run.sh
+
+RUN /etc/init.d/postfix start
+
+# Clean up
+RUN apt-get clean && \
+    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* && \
+    rm /var/log/lastlog /var/log/faillog
+
+# CMD ["/bin/bash", "/run.sh"]
+
+# Set default work directory
+WORKDIR /var
+
+EXPOSE 25