diff --git a/Dockerfile b/Dockerfile
index 684c3edd..b3d4e5c2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,6 +5,7 @@ ENV DEBIAN_FRONTEND noninteractive
 ENV VIRUSMAILS_DELETE_DELAY=7
 ENV ONE_DIR=0
 ENV ENABLE_POSTGREY=0
+ENV FETCHMAIL_POLL=300
 ENV POSTGREY_DELAY=300
 ENV POSTGREY_MAX_AGE=35
 ENV POSTGREY_TEXT="Delayed by postgrey"