diff --git a/data/conf/postfix/main.cf b/data/conf/postfix/main.cf
index 95301c43..bd8f76ed 100644
--- a/data/conf/postfix/main.cf
+++ b/data/conf/postfix/main.cf
@@ -20,6 +20,7 @@ broken_sasl_auth_clients = yes
 disable_vrfy_command = yes
 maximal_backoff_time = 1800s
 maximal_queue_lifetime = 5d
+delay_warning_time = 4h
 message_size_limit = 104857600
 milter_default_action = accept
 milter_protocol = 6