diff --git a/apps/emqx/test/emqx_persistent_session_SUITE.erl b/apps/emqx/test/emqx_persistent_session_SUITE.erl
index bd7ca1c46..3f4cbcd28 100644
--- a/apps/emqx/test/emqx_persistent_session_SUITE.erl
+++ b/apps/emqx/test/emqx_persistent_session_SUITE.erl
@@ -181,18 +181,23 @@ client_info(Key, Client) ->
     maps:get(Key, maps:from_list(emqtt:info(Client)), undefined).
 
 receive_messages(Count) ->
-    receive_messages(Count, []).
+    receive_messages(Count, 15000).
 
-receive_messages(0, Msgs) ->
-    Msgs;
-receive_messages(Count, Msgs) ->
+receive_messages(Count, Timeout) ->
+    Deadline = erlang:monotonic_time(millisecond) + Timeout,
+    receive_message_loop(Count, Deadline).
+
+receive_message_loop(0, _Deadline) ->
+    [];
+receive_message_loop(Count, Deadline) ->
+    Timeout = max(0, Deadline - erlang:monotonic_time(millisecond)),
     receive
         {publish, Msg} ->
-            receive_messages(Count - 1, [Msg | Msgs]);
+            [Msg | receive_message_loop(Count - 1, Deadline)];
         _Other ->
-            receive_messages(Count, Msgs)
-    after 15000 ->
-        Msgs
+            receive_message_loop(Count, Deadline)
+    after Timeout ->
+        []
     end.
 
 maybe_kill_connection_process(ClientId, Config) ->
@@ -229,16 +234,28 @@ wait_for_cm_unregister(ClientId, N) ->
             wait_for_cm_unregister(ClientId, N - 1)
     end.
 
-publish(Topic, Payloads) ->
-    publish(Topic, Payloads, false, 2).
+messages(Topic, Payloads) ->
+    messages(Topic, Payloads, ?QOS_2).
 
-publish(Topic, Payloads, WaitForUnregister, QoS) ->
-    Fun = fun(Client, Payload) ->
-        {ok, _} = emqtt:publish(Client, Topic, Payload, QoS)
+messages(Topic, Payloads, QoS) ->
+    [#mqtt_msg{topic = Topic, payload = P, qos = QoS} || P <- Payloads].
+
+publish(Topic, Payload) ->
+    publish(Topic, Payload, ?QOS_2).
+
+publish(Topic, Payload, QoS) ->
+    publish_many(messages(Topic, [Payload], QoS)).
+
+publish_many(Messages) ->
+    publish_many(Messages, false).
+
+publish_many(Messages, WaitForUnregister) ->
+    Fun = fun(Client, Message) ->
+        {ok, _} = emqtt:publish(Client, Message)
     end,
-    do_publish(Payloads, Fun, WaitForUnregister).
+    do_publish(Messages, Fun, WaitForUnregister).
 
-do_publish(Payloads = [_ | _], PublishFun, WaitForUnregister) ->
+do_publish(Messages = [_ | _], PublishFun, WaitForUnregister) ->
     %% Publish from another process to avoid connection confusion.
     {Pid, Ref} =
         spawn_monitor(
@@ -252,7 +269,7 @@ do_publish(Payloads = [_ | _], PublishFun, WaitForUnregister) ->
                     {port, 1883}
                 ]),
                 {ok, _} = emqtt:connect(Client),
-                lists:foreach(fun(Payload) -> PublishFun(Client, Payload) end, Payloads),
+                lists:foreach(fun(Message) -> PublishFun(Client, Message) end, Messages),
                 ok = emqtt:disconnect(Client),
                 %% Snabbkaffe sometimes fails unless all processes are gone.
                 case WaitForUnregister of
@@ -277,9 +294,7 @@ do_publish(Payloads = [_ | _], PublishFun, WaitForUnregister) ->
     receive
         {'DOWN', Ref, process, Pid, normal} -> ok;
         {'DOWN', Ref, process, Pid, What} -> error({failed_publish, What})
-    end;
-do_publish(Payload, PublishFun, WaitForUnregister) ->
-    do_publish([Payload], PublishFun, WaitForUnregister).
+    end.
 
 %%--------------------------------------------------------------------
 %% Test Cases
@@ -494,7 +509,7 @@ t_process_dies_session_expires(Config) ->
 
     maybe_kill_connection_process(ClientId, Config),
 
-    ok = publish(Topic, [Payload]),
+    ok = publish(Topic, Payload),
 
     timer:sleep(1100),
 
@@ -535,7 +550,7 @@ t_publish_while_client_is_gone_qos1(Config) ->
     ok = emqtt:disconnect(Client1),
     maybe_kill_connection_process(ClientId, Config),
 
-    ok = publish(Topic, [Payload1, Payload2], false, 1),
+    ok = publish_many(messages(Topic, [Payload1, Payload2], ?QOS_1)),
 
     {ok, Client2} = emqtt:start_link([
         {proto_ver, v5},
@@ -547,7 +562,7 @@ t_publish_while_client_is_gone_qos1(Config) ->
     {ok, _} = emqtt:ConnFun(Client2),
     Msgs = receive_messages(2),
     ?assertMatch([_, _], Msgs),
-    [Msg2, Msg1] = Msgs,
+    [Msg1, Msg2] = Msgs,
     ?assertEqual({ok, iolist_to_binary(Payload1)}, maps:find(payload, Msg1)),
     ?assertEqual({ok, 1}, maps:find(qos, Msg1)),
     ?assertEqual({ok, iolist_to_binary(Payload2)}, maps:find(payload, Msg2)),
@@ -555,6 +570,131 @@ t_publish_while_client_is_gone_qos1(Config) ->
 
     ok = emqtt:disconnect(Client2).
 
+t_publish_many_while_client_is_gone_qos1(Config) ->
+    %% A persistent session should receive all of the still unacked messages
+    %% for its subscriptions after the client dies or reconnects, in addition
+    %% to new messages that were published while the client was gone. The order
+    %% of the messages should be consistent across reconnects.
+    ClientId = ?config(client_id, Config),
+    ConnFun = ?config(conn_fun, Config),
+    {ok, Client1} = emqtt:start_link([
+        {proto_ver, v5},
+        {clientid, ClientId},
+        {properties, #{'Session-Expiry-Interval' => 30}},
+        {clean_start, true},
+        {auto_ack, false}
+        | Config
+    ]),
+    {ok, _} = emqtt:ConnFun(Client1),
+
+    STopics = [
+        <<"t/+/foo">>,
+        <<"msg/feed/#">>,
+        <<"loc/+/+/+">>
+    ],
+    [{ok, _, [?QOS_1]} = emqtt:subscribe(Client1, ST, ?QOS_1) || ST <- STopics],
+
+    Pubs1 = [
+        #mqtt_msg{topic = <<"t/42/foo">>, payload = <<"M1">>, qos = 1},
+        #mqtt_msg{topic = <<"t/42/foo">>, payload = <<"M2">>, qos = 1},
+        #mqtt_msg{topic = <<"msg/feed/me">>, payload = <<"M3">>, qos = 1},
+        #mqtt_msg{topic = <<"loc/1/2/42">>, payload = <<"M4">>, qos = 1},
+        #mqtt_msg{topic = <<"t/42/foo">>, payload = <<"M5">>, qos = 1},
+        #mqtt_msg{topic = <<"loc/3/4/5">>, payload = <<"M6">>, qos = 1},
+        #mqtt_msg{topic = <<"msg/feed/me">>, payload = <<"M7">>, qos = 1}
+    ],
+    ok = publish_many(Pubs1),
+    NPubs1 = length(Pubs1),
+
+    Msgs1 = receive_messages(NPubs1),
+    NMsgs1 = length(Msgs1),
+    ?assertEqual(NPubs1, NMsgs1),
+
+    ct:pal("Msgs1 = ~p", [Msgs1]),
+
+    %% TODO
+    %% This assertion doesn't currently hold because `emqx_ds` doesn't enforce
+    %% strict ordering reflecting client publishing order. Instead, per-topic
+    %% ordering is guaranteed per each client. In fact, this violates the MQTT
+    %% specification, but we deemed it acceptable for now.
+    %% ?assertMatch([
+    %%     #{payload := <<"M1">>},
+    %%     #{payload := <<"M2">>},
+    %%     #{payload := <<"M3">>},
+    %%     #{payload := <<"M4">>},
+    %%     #{payload := <<"M5">>},
+    %%     #{payload := <<"M6">>},
+    %%     #{payload := <<"M7">>}
+    %% ], Msgs1),
+
+    ?assertEqual(
+        get_topicwise_order(Pubs1),
+        get_topicwise_order(Msgs1),
+        Msgs1
+    ),
+
+    NAcked = 4,
+    [ok = emqtt:puback(Client1, PktId) || #{packet_id := PktId} <- lists:sublist(Msgs1, NAcked)],
+
+    %% Ensure that PUBACKs are propagated to the channel.
+    pong = emqtt:ping(Client1),
+
+    ok = emqtt:disconnect(Client1),
+    maybe_kill_connection_process(ClientId, Config),
+
+    Pubs2 = [
+        #mqtt_msg{topic = <<"loc/3/4/5">>, payload = <<"M8">>, qos = 1},
+        #mqtt_msg{topic = <<"t/100/foo">>, payload = <<"M9">>, qos = 1},
+        #mqtt_msg{topic = <<"t/100/foo">>, payload = <<"M10">>, qos = 1},
+        #mqtt_msg{topic = <<"msg/feed/friend">>, payload = <<"M11">>, qos = 1},
+        #mqtt_msg{topic = <<"msg/feed/me">>, payload = <<"M12">>, qos = 1}
+    ],
+    ok = publish_many(Pubs2),
+    NPubs2 = length(Pubs2),
+
+    {ok, Client2} = emqtt:start_link([
+        {proto_ver, v5},
+        {clientid, ClientId},
+        {properties, #{'Session-Expiry-Interval' => 30}},
+        {clean_start, false},
+        {auto_ack, false}
+        | Config
+    ]),
+    {ok, _} = emqtt:ConnFun(Client2),
+
+    %% Try to receive _at most_ `NPubs` messages.
+    %% There shouldn't be that much unacked messages in the replay anyway,
+    %% but it's an easy number to pick.
+    NPubs = NPubs1 + NPubs2,
+    Msgs2 = receive_messages(NPubs, _Timeout = 2000),
+    NMsgs2 = length(Msgs2),
+
+    ct:pal("Msgs2 = ~p", [Msgs2]),
+
+    ?assert(NMsgs2 < NPubs, Msgs2),
+    ?assert(NMsgs2 > NPubs2, Msgs2),
+    ?assert(NMsgs2 >= NPubs - NAcked, Msgs2),
+    NSame = NMsgs2 - NPubs2,
+    ?assertEqual(
+        [maps:with([packet_id, topic, payload], M) || M <- lists:nthtail(NMsgs1 - NSame, Msgs1)],
+        [maps:with([packet_id, topic, payload], M) || M <- lists:sublist(Msgs2, NSame)]
+    ),
+
+    ok = emqtt:disconnect(Client2).
+
+get_topicwise_order(Msgs) ->
+    maps:groups_from_list(fun get_msgpub_topic/1, fun get_msgpub_payload/1, Msgs).
+
+get_msgpub_topic(#mqtt_msg{topic = Topic}) ->
+    Topic;
+get_msgpub_topic(#{topic := Topic}) ->
+    Topic.
+
+get_msgpub_payload(#mqtt_msg{payload = Payload}) ->
+    Payload;
+get_msgpub_payload(#{payload := Payload}) ->
+    Payload.
+
 t_publish_while_client_is_gone(init, Config) -> skip_ds_tc(Config);
 t_publish_while_client_is_gone('end', _Config) -> ok.
 t_publish_while_client_is_gone(Config) ->
@@ -579,7 +719,7 @@ t_publish_while_client_is_gone(Config) ->
     ok = emqtt:disconnect(Client1),
     maybe_kill_connection_process(ClientId, Config),
 
-    ok = publish(Topic, [Payload1, Payload2]),
+    ok = publish_many(messages(Topic, [Payload1, Payload2])),
 
     {ok, Client2} = emqtt:start_link([
         {proto_ver, v5},
@@ -591,7 +731,7 @@ t_publish_while_client_is_gone(Config) ->
     {ok, _} = emqtt:ConnFun(Client2),
     Msgs = receive_messages(2),
     ?assertMatch([_, _], Msgs),
-    [Msg2, Msg1] = Msgs,
+    [Msg1, Msg2] = Msgs,
     ?assertEqual({ok, iolist_to_binary(Payload1)}, maps:find(payload, Msg1)),
     ?assertEqual({ok, 2}, maps:find(qos, Msg1)),
     ?assertEqual({ok, iolist_to_binary(Payload2)}, maps:find(payload, Msg2)),