diff --git a/files/Dockerfile b/files/Dockerfile
index 901143a..97b92b8 100644
--- a/files/Dockerfile
+++ b/files/Dockerfile
@@ -17,4 +17,6 @@ RUN echo "_dev_null: /dev/null" > /etc/aliases \
   && cp /etc/ssl/private/ssl-cert-snakeoil.key /ssl/key.pem
 
 VOLUME /etc/postfix /ssl
+EXPOSE 25/tcp 587/tcp
+
 CMD postfix start-fg