diff --git a/example.env b/example.env
index 8ed6bc7..ac08ee9 100644
--- a/example.env
+++ b/example.env
@@ -60,6 +60,7 @@ ETHERPAD_NODE_ENV=production
 ETHERPAD_ADMIN_PASSWORD=
 
 # The ports on which to run apps
+# See also: LOCAL_SMTP_PORT
 ETHERPAD_PORT=9001
 HTTP_PORT=8080
 GEMINI_PORT=1965