FROM debian:bookworm-slim

# "No configuration" skips postfix's interactive debconf setup during install;
# the entrypoint configures main.cf/transport itself via postconf.
RUN echo "postfix postfix/main_mailer_type select No configuration" | debconf-set-selections \
    && DEBIAN_FRONTEND=noninteractive apt-get update \
    && apt-get install -y --no-install-recommends postfix \
    && rm -rf /var/lib/apt/lists/*

COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh

EXPOSE 25
ENTRYPOINT ["/entrypoint.sh"]