diff --git a/addons/mail/static/src/core/common/message_model.js b/addons/mail/static/src/core/common/message_model.js
index 7925a447dfb..baa1b586946 100644
--- a/addons/mail/static/src/core/common/message_model.js
+++ b/addons/mail/static/src/core/common/message_model.js
@@ -109,6 +109,14 @@ export class Message extends Record {
     linkPreviews = Record.many("LinkPreview", { inverse: "message" });
     /** @type {number[]} */
     needaction_partner_ids = [];
+    originThread = Record.one("Thread", {
+        inverse: "allMessages",
+        compute() {
+            if (this.model && this.res_id) {
+                return { model: this.model, id: this.res_id };
+            }
+        },
+    });
     /** @type {number[]} */
     history_partner_ids = [];
     parentMessage = Record.one("Message");
@@ -241,10 +249,6 @@ export class Message extends Record {
         return candidates.has(this.subject?.toLowerCase());
     }
 
-    get originThread() {
-        return this._store.Thread.get({ model: this.model, id: this.res_id });
-    }
-
     get resUrl() {
         return `${url("/web")}#model=${this.model}&id=${this.res_id}`;
     }
diff --git a/addons/mail/static/src/core/common/thread.js b/addons/mail/static/src/core/common/thread.js
index c8b08c6c118..40e4828f935 100644
--- a/addons/mail/static/src/core/common/thread.js
+++ b/addons/mail/static/src/core/common/thread.js
@@ -81,16 +81,24 @@ export class Thread extends Component {
          * scrollable (in other cases).
          */
         this.scrollableRef = this.props.scrollRef ?? useRef("messages");
-        this.loadOlderState = useVisible("load-older", () => {
-            if (this.loadOlderState.isVisible && !this.isJumpingRecent) {
-                this.threadService.fetchMoreMessages(this.props.thread);
-            }
-        });
-        this.loadNewerState = useVisible("load-newer", () => {
-            if (this.loadNewerState.isVisible && !this.isJumpingRecent) {
-                this.threadService.fetchMoreMessages(this.props.thread, "newer");
-            }
-        });
+        this.loadOlderState = useVisible(
+            "load-older",
+            () => {
+                if (this.loadOlderState.isVisible && !this.isJumpingRecent) {
+                    this.threadService.fetchMoreMessages(this.props.thread);
+                }
+            },
+            { init: null }
+        );
+        this.loadNewerState = useVisible(
+            "load-newer",
+            () => {
+                if (this.loadNewerState.isVisible && !this.isJumpingRecent) {
+                    this.threadService.fetchMoreMessages(this.props.thread, "newer");
+                }
+            },
+            { init: null }
+        );
         this.presentThresholdState = useVisible(
             "present-treshold",
             () => this.updateShowJumpPresent(),
diff --git a/addons/mail/static/src/core/common/thread_model.js b/addons/mail/static/src/core/common/thread_model.js
index 2bf712c9214..3e24253c1d9 100644
--- a/addons/mail/static/src/core/common/thread_model.js
+++ b/addons/mail/static/src/core/common/thread_model.js
@@ -143,6 +143,9 @@ export class Thread extends Record {
     uuid;
     /** @type {string} */
     model;
+    allMessages = Record.many("Message", {
+        inverse: "originThread",
+    });
     /** @type {boolean} */
     areAttachmentsLoaded = false;
     attachments = Record.many("Attachment");
@@ -398,6 +401,14 @@ export class Thread extends Record {
         return [...this.messages].reverse().find((msg) => Number.isInteger(msg.id));
     }
 
+    get newestPersistentNotEmptyOfAllMessage() {
+        const allPersistentMessages = this.allMessages.filter(
+            (message) => Number.isInteger(message.id) && !message.isEmpty
+        );
+        allPersistentMessages.sort((m1, m2) => m2.id - m1.id);
+        return allPersistentMessages[0];
+    }
+
     get oldestPersistentMessage() {
         return this.messages.find((msg) => Number.isInteger(msg.id));
     }
diff --git a/addons/mail/static/src/core/common/thread_service.js b/addons/mail/static/src/core/common/thread_service.js
index e91e6c77f00..e37b5637795 100644
--- a/addons/mail/static/src/core/common/thread_service.js
+++ b/addons/mail/static/src/core/common/thread_service.js
@@ -83,12 +83,13 @@ export class ThreadService {
     /**
      * @param {import("models").Thread} thread
      */
-    async markAsRead(thread) {
-        if (!thread.isLoaded) {
-            await thread.isLoadedDeferred;
-            await new Promise(setTimeout);
+    markAsRead(thread) {
+        const newestPersistentMessage = thread.newestPersistentNotEmptyOfAllMessage;
+        if (!newestPersistentMessage && !thread.isLoaded) {
+            thread.isLoadedDeferred
+                .then(() => new Promise(setTimeout))
+                .then(() => this.markAsRead(thread));
         }
-        const newestPersistentMessage = thread.newestPersistentMessage;
         thread.seen_message_id = newestPersistentMessage?.id ?? false;
         if (
             thread.message_unread_counter > 0 &&
@@ -98,13 +99,15 @@ export class ThreadService {
             this.rpc("/discuss/channel/set_last_seen_message", {
                 channel_id: thread.id,
                 last_message_id: newestPersistentMessage.id,
-            }).then(() => {
-                this.updateSeen(thread, newestPersistentMessage.id);
-            }).catch((e) => {
-                if (e.code !== 404) {
-                    throw e;
-                }
-            });
+            })
+                .then(() => {
+                    this.updateSeen(thread, newestPersistentMessage.id);
+                })
+                .catch((e) => {
+                    if (e.code !== 404) {
+                        throw e;
+                    }
+                });
         } else if (newestPersistentMessage) {
             this.updateSeen(thread);
         }
@@ -113,7 +116,7 @@ export class ThreadService {
         }
     }
 
-    updateSeen(thread, lastSeenId = thread.newestPersistentMessage?.id) {
+    updateSeen(thread, lastSeenId = thread.newestPersistentNotEmptyOfAllMessage?.id) {
         const lastReadIndex = thread.messages.findIndex((message) => message.id === lastSeenId);
         let newNeedactionCounter = 0;
         let newUnreadCounter = 0;
@@ -143,7 +146,7 @@ export class ThreadService {
             needactionMessages: [],
             message_unread_counter: 0,
             message_needaction_counter: 0,
-            seen_message_id: thread.newestPersistentMessage?.id,
+            seen_message_id: thread.newestPersistentNotEmptyOfAllMessage?.id,
         });
     }
 
@@ -327,15 +330,9 @@ export class ThreadService {
             for (const preview of previews) {
                 const thread = this.store.Thread.get({ model: "discuss.channel", id: preview.id });
                 const message = this.store.Message.insert(preview.last_message, { html: true });
-                if (!thread.isLoaded) {
-                    thread.messages.push(message);
-                    if (message.isNeedaction) {
-                        thread.needactionMessages.add(message);
-                    }
+                if (message.isNeedaction) {
+                    thread.needactionMessages.add(message);
                 }
-                thread.isLoaded = true;
-                thread.loadOlder = true;
-                thread.status = "ready";
             }
         }
     });
@@ -867,10 +864,16 @@ export class ThreadService {
         }
         if (thread?.model === "discuss.channel") {
             if (persona.type === "partner") {
-                return url(`/discuss/channel/${thread.id}/partner/${persona.id}/avatar_128`, urlParams);
+                return url(
+                    `/discuss/channel/${thread.id}/partner/${persona.id}/avatar_128`,
+                    urlParams
+                );
             }
             if (persona.type === "guest") {
-                return url(`/discuss/channel/${thread.id}/guest/${persona.id}/avatar_128`, urlParams);
+                return url(
+                    `/discuss/channel/${thread.id}/guest/${persona.id}/avatar_128`,
+                    urlParams
+                );
             }
         }
         if (persona.type === "partner" && persona?.id) {
diff --git a/addons/mail/static/src/core/web/messaging_menu.js b/addons/mail/static/src/core/web/messaging_menu.js
index 0204e306b07..3039adf2aa8 100644
--- a/addons/mail/static/src/core/web/messaging_menu.js
+++ b/addons/mail/static/src/core/web/messaging_menu.js
@@ -167,14 +167,28 @@ export class MessagingMenu extends Component {
             if (b.message_unread_counter > 0 && a.message_unread_counter === 0) {
                 return 1;
             }
-            if (!a.newestPersistentMessage?.datetime && b.newestPersistentMessage?.datetime) {
+            if (
+                !a.newestPersistentNotEmptyOfAllMessage?.datetime &&
+                b.newestPersistentNotEmptyOfAllMessage?.datetime
+            ) {
                 return 1;
             }
-            if (!b.newestPersistentMessage?.datetime && a.newestPersistentMessage?.datetime) {
+            if (
+                !b.newestPersistentNotEmptyOfAllMessage?.datetime &&
+                a.newestPersistentNotEmptyOfAllMessage?.datetime
+            ) {
                 return -1;
             }
-            if (a.newestPersistentMessage?.datetime && b.newestPersistentMessage?.datetime) {
-                return b.newestPersistentMessage.datetime - a.newestPersistentMessage.datetime;
+            if (
+                a.newestPersistentNotEmptyOfAllMessage?.datetime &&
+                b.newestPersistentNotEmptyOfAllMessage?.datetime &&
+                a.newestPersistentNotEmptyOfAllMessage?.datetime !==
+                    b.newestPersistentNotEmptyOfAllMessage?.datetime
+            ) {
+                return (
+                    b.newestPersistentNotEmptyOfAllMessage.datetime -
+                    a.newestPersistentNotEmptyOfAllMessage.datetime
+                );
             }
             return b.localId > a.localId ? 1 : -1;
         });
diff --git a/addons/mail/static/src/core/web/messaging_menu.xml b/addons/mail/static/src/core/web/messaging_menu.xml
index aa5d108a47f..0ea22574f0e 100644
--- a/addons/mail/static/src/core/web/messaging_menu.xml
+++ b/addons/mail/static/src/core/web/messaging_menu.xml
@@ -72,7 +72,7 @@
                 </t>
             </t>
             <t t-foreach="threads" t-as="thread" t-key="thread.localId">
-                <t t-set="message" t-value="thread.isChatChannel or (thread.type === 'channel' and thread.needactionMessages.length === 0) ? thread.newestMessage : thread.needactionMessages.at(-1)"/>
+                <t t-set="message" t-value="thread.isChatChannel or (thread.type === 'channel' and thread.needactionMessages.length === 0) ? thread.newestPersistentNotEmptyOfAllMessage : thread.needactionMessages.at(-1)"/>
                 <NotificationItem
                     body="message?.inlineBody"
                     counter="thread.needactionCounter"
diff --git a/addons/mail/static/src/utils/common/hooks.js b/addons/mail/static/src/utils/common/hooks.js
index 7687698d77d..5f00c681fac 100644
--- a/addons/mail/static/src/utils/common/hooks.js
+++ b/addons/mail/static/src/utils/common/hooks.js
@@ -6,6 +6,7 @@ import {
     onWillPatch,
     onWillUnmount,
     useComponent,
+    useEffect,
     useRef,
     useState,
 } from "@odoo/owl";
@@ -165,37 +166,25 @@ export function useAutoScroll(refName, shouldScrollPredicate = () => true) {
 export function useVisible(refName, cb, { init = false } = {}) {
     const ref = useRef(refName);
     const state = { isVisible: init };
-    const observer = new IntersectionObserver((entries) => {
-        for (const entry of entries) {
-            const newVal = entry.isIntersecting;
-            if (state.isVisible !== newVal) {
-                state.isVisible = newVal;
-                cb();
-            }
-        }
-    });
-    let el;
-    onMounted(observe);
-    onWillUnmount(() => {
-        if (!el) {
-            return;
-        }
-        observer.unobserve(el);
-    });
-    onPatched(observe);
-
-    function observe() {
-        if (ref.el !== el) {
-            if (el) {
-                observer.unobserve(el);
-                state.isVisible = false;
-            }
-            if (ref.el) {
-                observer.observe(ref.el);
-            }
-        }
-        el = ref.el;
+    function setValue(value) {
+        state.isVisible = value;
+        cb();
     }
+    const observer = new IntersectionObserver((entries) => {
+        setValue(entries.at(-1).isIntersecting);
+    });
+    useEffect(
+        (el) => {
+            if (el) {
+                observer.observe(el);
+                return () => {
+                    setValue(false);
+                    observer.unobserve(el);
+                };
+            }
+        },
+        () => [ref.el]
+    );
     return state;
 }
 
diff --git a/addons/mail/static/tests/chat_window/chat_window_tests.js b/addons/mail/static/tests/chat_window/chat_window_tests.js
index 12ecf28c82f..f47d9446a4e 100644
--- a/addons/mail/static/tests/chat_window/chat_window_tests.js
+++ b/addons/mail/static/tests/chat_window/chat_window_tests.js
@@ -982,7 +982,7 @@ QUnit.test("chat window: scroll conservation on toggle discuss", async () => {
     const { openDiscuss, openView } = await start();
     await click(".o_menu_systray .dropdown-toggle:has(i[aria-label='Messages'])");
     await click(".o-mail-NotificationItem");
-    await contains(".o-mail-Message", { count: 31 });
+    await contains(".o-mail-Message", { count: 30 });
     await contains(".o-mail-ChatWindow .o-mail-Thread", { scroll: "bottom" });
     await scroll(".o-mail-ChatWindow .o-mail-Thread", 142);
     openDiscuss(null);
@@ -992,7 +992,7 @@ QUnit.test("chat window: scroll conservation on toggle discuss", async () => {
         res_model: "discuss.channel",
         views: [[false, "list"]],
     });
-    await contains(".o-mail-Message", { count: 31 });
+    await contains(".o-mail-Message", { count: 30 });
     await contains(".o-mail-ChatWindow .o-mail-Thread", { scroll: 142 });
 });
 
@@ -1011,7 +1011,7 @@ QUnit.test(
         await start();
         await click(".o_menu_systray .dropdown-toggle:has(i[aria-label='Messages'])");
         await click(".o-mail-NotificationItem");
-        await contains(".o-mail-Message", { count: 31 });
+        await contains(".o-mail-Message", { count: 30 });
         await contains(".o-mail-ChatWindow .o-mail-Thread", { scroll: "bottom" });
         await scroll(".o-mail-ChatWindow .o-mail-Thread", 142);
         // fold chat window
@@ -1020,7 +1020,7 @@ QUnit.test(
         await contains(".o-mail-ChatWindow .o-mail-Thread", { count: 0 });
         // unfold chat window
         await click(".o-mail-ChatWindow-command[title='Open']");
-        await contains(".o-mail-Message", { count: 31 });
+        await contains(".o-mail-Message", { count: 30 });
         await contains(".o-mail-ChatWindow .o-mail-Thread", { scroll: 142 });
     }
 );
@@ -1040,7 +1040,7 @@ QUnit.test(
         const { openDiscuss, openView } = await start();
         await click(".o_menu_systray .dropdown-toggle:has(i[aria-label='Messages'])");
         await click(".o-mail-NotificationItem");
-        await contains(".o-mail-Message", { count: 31 });
+        await contains(".o-mail-Message", { count: 30 });
         await contains(".o-mail-ChatWindow .o-mail-Thread", { scroll: "bottom" });
         await scroll(".o-mail-ChatWindow .o-mail-Thread", 142);
         // fold chat window
@@ -1054,7 +1054,7 @@ QUnit.test(
         });
         // unfold chat window
         await click(".o-mail-ChatWindow-command[title='Open']");
-        await contains(".o-mail-ChatWindow .o-mail-Message", { count: 31 });
+        await contains(".o-mail-ChatWindow .o-mail-Message", { count: 30 });
         await contains(".o-mail-ChatWindow .o-mail-Thread", { scroll: 142 });
     }
 );
diff --git a/addons/mail/static/tests/discuss/core/web/messaging_menu_tests.js b/addons/mail/static/tests/discuss/core/web/messaging_menu_tests.js
index 614462dbf7b..4a49533407e 100644
--- a/addons/mail/static/tests/discuss/core/web/messaging_menu_tests.js
+++ b/addons/mail/static/tests/discuss/core/web/messaging_menu_tests.js
@@ -5,7 +5,7 @@ import { startServer } from "@bus/../tests/helpers/mock_python_environment";
 import { patchUiSize } from "@mail/../tests/helpers/patch_ui_size";
 import { start } from "@mail/../tests/helpers/test_utils";
 
-import { triggerHotkey } from "@web/../tests/helpers/utils";
+import { patchWithCleanup, triggerHotkey } from "@web/../tests/helpers/utils";
 import { click, contains, insertText } from "@web/../tests/utils";
 
 QUnit.module("messaging menu");
@@ -58,3 +58,98 @@ QUnit.test("new message [REQUIRE FOCUS]", async () => {
     await click(".o-mail-MessagingMenu button", { text: "New Message" });
     await contains(".o-mail-ChatWindow .o-discuss-ChannelSelector input:focus");
 });
+
+QUnit.test("channel preview ignores empty message", async () => {
+    const pyEnv = await startServer();
+    const partnerId = pyEnv["res.partner"].create({ name: "Demo" });
+    const channelId = pyEnv["discuss.channel"].create({
+        name: "General",
+    });
+    pyEnv["mail.message"].create({
+        author_id: partnerId,
+        body: "<p>before last</p>",
+        model: "discuss.channel",
+        res_id: channelId,
+    });
+    pyEnv["mail.message"].create({
+        author_id: partnerId,
+        body: "<p></p>",
+        model: "discuss.channel",
+        res_id: channelId,
+    });
+    const { openDiscuss } = await start();
+    await openDiscuss(channelId);
+    await contains(".o-mail-Message", { text: "before last" });
+    await click(".o_menu_systray .dropdown-toggle:has(i[aria-label='Messages'])");
+    await contains(".o-mail-NotificationItem-text", { text: "Demo: before last" });
+});
+
+QUnit.test("channel preview ignores transient message", async () => {
+    const pyEnv = await startServer();
+    const partnerId = pyEnv["res.partner"].create({ name: "Demo" });
+    const channelId = pyEnv["discuss.channel"].create({
+        name: "General",
+    });
+    pyEnv["mail.message"].create({
+        author_id: partnerId,
+        body: "<p>test</p>",
+        model: "discuss.channel",
+        res_id: channelId,
+    });
+    const { openDiscuss } = await start();
+    await openDiscuss(channelId);
+    await insertText(".o-mail-Composer-input", "/who");
+    await click(".o-mail-Composer-send:enabled");
+    await contains(".o_mail_notification", { text: "You are alone in this channel." });
+    await click(".o_menu_systray .dropdown-toggle:has(i[aria-label='Messages'])");
+    await contains(".o-mail-NotificationItem-text", { text: "Demo: test" });
+});
+
+QUnit.test("channel preview ignores messages from the past", async () => {
+    // make scroll behavior instantaneous.
+    patchWithCleanup(Element.prototype, {
+        scrollIntoView() {
+            return super.scrollIntoView(true);
+        },
+    });
+    const pyEnv = await startServer();
+    const channelId = pyEnv["discuss.channel"].create({ name: "General" });
+    const messageId = pyEnv["mail.message"].create({
+        body: "first message",
+        message_type: "comment",
+        model: "discuss.channel",
+        res_id: channelId,
+    });
+    for (let i = 0; i < 100; i++) {
+        pyEnv["mail.message"].create({
+            body: `message ${i}`,
+            message_type: "comment",
+            model: "discuss.channel",
+            res_id: channelId,
+        });
+    }
+    pyEnv["mail.message"].create({
+        body: "last message",
+        message_type: "comment",
+        model: "discuss.channel",
+        parent_id: messageId,
+        res_id: channelId,
+    });
+    const { env, openDiscuss } = await start();
+    await openDiscuss(channelId);
+    await contains(".o-mail-Message", { count: 30 });
+    await contains(".o-mail-Message", { text: "last message" });
+    await contains(".o-mail-Thread", { scroll: "bottom" });
+    await click(".o-mail-MessageInReply-content", { text: "first message" });
+    await contains(".o-mail-Message", { text: "last message", count: 0 });
+    await click(".o_menu_systray .dropdown-toggle:has(i[aria-label='Messages'])");
+    await contains(".o-mail-NotificationItem-text", { text: "You: last message" });
+    pyEnv.withUser(pyEnv.currentUserId, () =>
+        env.services.rpc("/mail/message/post", {
+            post_data: { body: "new message", message_type: "comment" },
+            thread_id: channelId,
+            thread_model: "discuss.channel",
+        })
+    );
+    await contains(".o-mail-NotificationItem-text", { text: "You: new message" });
+});
diff --git a/addons/mail/static/tests/messaging_menu/messaging_menu_tests.js b/addons/mail/static/tests/messaging_menu/messaging_menu_tests.js
index e8cea29a527..fc6c3c6972a 100644
--- a/addons/mail/static/tests/messaging_menu/messaging_menu_tests.js
+++ b/addons/mail/static/tests/messaging_menu/messaging_menu_tests.js
@@ -427,10 +427,11 @@ QUnit.test("mark unread channel as read", async (assert) => {
             Command.create({ message_unread_counter: 1, partner_id: pyEnv.currentPartnerId }),
             Command.create({ partner_id: partnerId }),
         ],
+        name: "My Channel",
     });
     const [messagId_1] = pyEnv["mail.message"].create([
-        { author_id: partnerId, model: "discuss.channel", res_id: channelId },
-        { author_id: partnerId, model: "discuss.channel", res_id: channelId },
+        { author_id: partnerId, body: "not empty", model: "discuss.channel", res_id: channelId },
+        { author_id: partnerId, body: "not empty", model: "discuss.channel", res_id: channelId },
     ]);
     const [currentMemberId] = pyEnv["discuss.channel.member"].search([
         ["channel_id", "=", channelId],
@@ -447,8 +448,8 @@ QUnit.test("mark unread channel as read", async (assert) => {
     await click(".o_menu_systray i[aria-label='Messages']");
     await triggerEvents(".o-mail-NotificationItem", ["mouseenter"]);
     await click(".o-mail-NotificationItem [title='Mark As Read']");
-    assert.verifySteps(["set_last_seen_message"]);
     await contains(".o-mail-NotificationItem.text-muted");
+    assert.verifySteps(["set_last_seen_message"]);
     await triggerEvents(".o-mail-NotificationItem", ["mouseenter"]);
     await contains(".o-mail-NotificationItem [title='Mark As Read']", { count: 0 });
     await contains(".o-mail-ChatWindow", { count: 0 });
diff --git a/addons/mail/static/tests/messaging_menu/notification_tests.js b/addons/mail/static/tests/messaging_menu/notification_tests.js
index 4426fc76dbf..3e6a68d5be4 100644
--- a/addons/mail/static/tests/messaging_menu/notification_tests.js
+++ b/addons/mail/static/tests/messaging_menu/notification_tests.js
@@ -248,11 +248,13 @@ QUnit.test("marked as read thread notifications are ordered by last message date
     ]);
     pyEnv["mail.message"].create([
         {
+            body: "not empty",
             date: "2019-01-01 00:00:00",
             model: "discuss.channel",
             res_id: channelId_1,
         },
         {
+            body: "not empty",
             date: "2020-01-01 00:00:00",
             model: "discuss.channel",
             res_id: channelId_2,