INIT: adding first Dockerfile to set up basic Debian 10 slim image

.gitignore

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+/*.code-workspace

Dockerfile

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+FROM debian:10-slim
+
+LABEL description "Simple mailserver in a mono Docker image" \
+      maintainer "behringer24 <abe@activecube.de"
+
+ARG DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get install -y -q --no-install-recommends \
+    postfix postfix-mysql \
+    dovecot-core dovecot-imapd dovecot-mysql dovecot-pop3d \
+    && rm -rf /var/spool/postfix \
+    && ln -s /var/mail/postfix/spool /var/spool/postfix \
+    && apt-get autoremove -y \
+    && apt-get clean \
+    && rm -rf /tmp/* /var/lib/apt/lists/* /var/cache/debconf/*-old
+
+EXPOSE 25 143 465 587 993 4190 11334