diff --git a/apps/emqx_retainer/src/emqx_retainer_schema.erl b/apps/emqx_retainer/src/emqx_retainer_schema.erl
index 1c5d8e55f..47540b0ec 100644
--- a/apps/emqx_retainer/src/emqx_retainer_schema.erl
+++ b/apps/emqx_retainer/src/emqx_retainer_schema.erl
@@ -81,6 +81,7 @@ fields("retainer") ->
                 #{
                     required => false,
                     desc => ?DESC(delivery_rate),
+                    default => <<"1000/s">>,
                     example => <<"1000/s">>,
                     aliases => [deliver_rate]
                 }
diff --git a/apps/emqx_retainer/test/emqx_retainer_SUITE.erl b/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
index 2818f6bfa..c76ba90c6 100644
--- a/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
+++ b/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
@@ -256,61 +256,67 @@ t_wildcard_subscription(_) ->
     ok = emqtt:disconnect(C1).
 
 t_message_expiry(_) ->
-    {ok, C1} = emqtt:start_link([{clean_start, true}, {proto_ver, v5}]),
-    {ok, _} = emqtt:connect(C1),
+    ConfMod = fun(Conf) ->
+        Conf#{<<"delivery_rate">> := <<"infinity">>}
+    end,
+    Case = fun() ->
+        {ok, C1} = emqtt:start_link([{clean_start, true}, {proto_ver, v5}]),
+        {ok, _} = emqtt:connect(C1),
 
-    emqtt:publish(
-        C1,
-        <<"retained/0">>,
-        #{'Message-Expiry-Interval' => 0},
-        <<"don't expire">>,
-        [{qos, 0}, {retain, true}]
-    ),
-    emqtt:publish(
-        C1,
-        <<"retained/1">>,
-        #{'Message-Expiry-Interval' => 2},
-        <<"expire">>,
-        [{qos, 0}, {retain, true}]
-    ),
-    emqtt:publish(
-        C1,
-        <<"retained/2">>,
-        #{'Message-Expiry-Interval' => 5},
-        <<"don't expire">>,
-        [{qos, 0}, {retain, true}]
-    ),
-    emqtt:publish(
-        C1,
-        <<"retained/3">>,
-        <<"don't expire">>,
-        [{qos, 0}, {retain, true}]
-    ),
-    emqtt:publish(
-        C1,
-        <<"$SYS/retained/4">>,
-        <<"don't expire">>,
-        [{qos, 0}, {retain, true}]
-    ),
+        emqtt:publish(
+            C1,
+            <<"retained/0">>,
+            #{'Message-Expiry-Interval' => 0},
+            <<"don't expire">>,
+            [{qos, 0}, {retain, true}]
+        ),
+        emqtt:publish(
+            C1,
+            <<"retained/1">>,
+            #{'Message-Expiry-Interval' => 2},
+            <<"expire">>,
+            [{qos, 0}, {retain, true}]
+        ),
+        emqtt:publish(
+            C1,
+            <<"retained/2">>,
+            #{'Message-Expiry-Interval' => 5},
+            <<"don't expire">>,
+            [{qos, 0}, {retain, true}]
+        ),
+        emqtt:publish(
+            C1,
+            <<"retained/3">>,
+            <<"don't expire">>,
+            [{qos, 0}, {retain, true}]
+        ),
+        emqtt:publish(
+            C1,
+            <<"$SYS/retained/4">>,
+            <<"don't expire">>,
+            [{qos, 0}, {retain, true}]
+        ),
 
-    {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained/+">>, 0),
-    {ok, #{}, [0]} = emqtt:subscribe(C1, <<"$SYS/retained/+">>, 0),
-    ?assertEqual(5, length(receive_messages(5))),
-    {ok, #{}, [0]} = emqtt:unsubscribe(C1, <<"retained/+">>),
-    {ok, #{}, [0]} = emqtt:unsubscribe(C1, <<"$SYS/retained/+">>),
+        {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained/+">>, 0),
+        {ok, #{}, [0]} = emqtt:subscribe(C1, <<"$SYS/retained/+">>, 0),
+        ?assertEqual(5, length(receive_messages(5))),
+        {ok, #{}, [0]} = emqtt:unsubscribe(C1, <<"retained/+">>),
+        {ok, #{}, [0]} = emqtt:unsubscribe(C1, <<"$SYS/retained/+">>),
 
-    timer:sleep(3000),
-    {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained/+">>, 0),
-    {ok, #{}, [0]} = emqtt:subscribe(C1, <<"$SYS/retained/+">>, 0),
-    ?assertEqual(4, length(receive_messages(5))),
+        timer:sleep(3000),
+        {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained/+">>, 0),
+        {ok, #{}, [0]} = emqtt:subscribe(C1, <<"$SYS/retained/+">>, 0),
+        ?assertEqual(4, length(receive_messages(5))),
 
-    emqtt:publish(C1, <<"retained/0">>, <<"">>, [{qos, 0}, {retain, true}]),
-    emqtt:publish(C1, <<"retained/1">>, <<"">>, [{qos, 0}, {retain, true}]),
-    emqtt:publish(C1, <<"retained/2">>, <<"">>, [{qos, 0}, {retain, true}]),
-    emqtt:publish(C1, <<"retained/3">>, <<"">>, [{qos, 0}, {retain, true}]),
-    emqtt:publish(C1, <<"$SYS/retained/4">>, <<"">>, [{qos, 0}, {retain, true}]),
+        emqtt:publish(C1, <<"retained/0">>, <<"">>, [{qos, 0}, {retain, true}]),
+        emqtt:publish(C1, <<"retained/1">>, <<"">>, [{qos, 0}, {retain, true}]),
+        emqtt:publish(C1, <<"retained/2">>, <<"">>, [{qos, 0}, {retain, true}]),
+        emqtt:publish(C1, <<"retained/3">>, <<"">>, [{qos, 0}, {retain, true}]),
+        emqtt:publish(C1, <<"$SYS/retained/4">>, <<"">>, [{qos, 0}, {retain, true}]),
 
-    ok = emqtt:disconnect(C1).
+        ok = emqtt:disconnect(C1)
+    end,
+    with_conf(ConfMod, Case).
 
 t_message_expiry_2(_) ->
     ConfMod = fun(Conf) ->
@@ -410,6 +416,7 @@ t_flow_control(_) ->
     JsonCfg = make_limiter_json(<<"1/1s">>),
     emqx_limiter_server:add_bucket(emqx_retainer, internal, LimiterCfg),
     emqx_retainer:update_config(#{
+        <<"delivery_rate">> => <<"1/1s">>,
         <<"flow_control">> =>
             #{
                 <<"batch_read_number">> => 1,