diff --git a/config/mosquitto/mosquitto.conf b/config/mosquitto/mosquitto.conf
index 8f6cfc6..2cb9389 100644
--- a/config/mosquitto/mosquitto.conf
+++ b/config/mosquitto/mosquitto.conf
@@ -12,3 +12,11 @@ auth_opt_jwt_getuser_uri /api/engine/v2/mqtt/mqtt_user
 auth_opt_jwt_aclcheck_uri /api/engine/v2/mqtt/mqtt_access
 auth_opt_jwt_response_mode status
 auth_opt_jwt_params_mode form
+
+# A client subscribing is sent every retained message under its filter at
+# once, and mosquitto drops whatever does not fit its outgoing queue (1000
+# messages by default) without telling it. Large sites retain far more than
+# that, so a client subscribing widely (stagehand's hot list, source clearing
+# or sweeping retained state) saw only part of it. A client that needs more
+# can subscribe more narrowly, or refresh.
+max_queued_messages 10000