fixed postfix configuration

core/Dockerfile

@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.3-labs
+# syntax=docker.io/docker/dockerfile:1.5.2
 FROM ubuntu:20.04
 RUN <<EOF
 export DEBIAN_FRONTEND=noninteractive 
@@ -19,10 +19,13 @@ EOF
 # use envsubst in entrypoint script to convert config templates to actual config files
 COPY --chmod=0775 entrypoint.sh /entrypoint.sh
 # https://documentation.kopano.io/kopanocore_administrator_manual/configure_kc_components.html#configure-kopano-dagent-for-delivery-via-unix-socket
-EXPOSE 236     # mapi (client-server)
-EXPOSE 237     # tls_mapi (server-server)
-EXPOSE 2003    # lmtp (dagent)
+# mapi (client-server)
+#EXPOSE 236
+# tls_mapi (server-server)
+#EXPOSE 237
+# lmtp (dagent)
+#EXPOSE 2003
 VOLUME /etc/kopano
 VOLUME /var/lib/kopano/attachments
 ENTRYPOINT ["/entrypoint.sh"]
-CMD ["/usr/sbin/kopano-server"]
+CMD ["bash"]