[faas#36] faas-smtp - support for SMTP relay.

Dockerfile

@@ -38,8 +38,9 @@ RUN \
 COPY ./conf/etc/supervisord.conf /etc/supervisord.conf
 COPY ./conf/etc/entrypoint /etc/entrypoint
 COPY ./conf/etc/aliases /etc/aliases
+COPY ./conf/etc/postfix/master.cf /etc/postfix
 
-EXPOSE 25/tcp
+EXPOSE 25 587
 
 ENTRYPOINT ["/etc/entrypoint"]