diff --git a/Dockerfile b/Dockerfile
index f927e0a..42cb017 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -13,7 +13,7 @@ FROM alpine
 COPY --from=0 /webmention-filer/target/release/webmention-filer /usr/bin/
 COPY send-daily-mail.sh send-daily-mail.sh
 
-RUN apk add mailx
+RUN apk add mailx postfix
 
 USER 1000:1000
 EXPOSE 8000