diff --git a/addons/mail/static/src/core/common/message.xml b/addons/mail/static/src/core/common/message.xml
index 45b3fbfa3e7..ade64face50 100644
--- a/addons/mail/static/src/core/common/message.xml
+++ b/addons/mail/static/src/core/common/message.xml
@@ -19,10 +19,10 @@
                             <img class="o-mail-Message-avatar w-100 h-100 rounded" t-att-src="authorAvatarUrl" t-att-class="authorAvatarAttClass"/>
                         </div>
                         <t t-elif="!message.isTransient">
-                            <small t-if="isActive and props.showDates" class="o-mail-Message-date text-muted opacity-75 ms-2">
+                            <small t-if="isActive and props.showDates" class="o-mail-Message-date text-muted opacity-75">
                                 <t t-esc="messageService.dateSimple(message)"/>
                             </small>
-                            <div t-else="" class="ms-2">
+                            <div t-else="">
                                 <MessageSeenIndicator
                                     t-if="props.message.isSelfAuthored and props.thread"
                                     message="props.message"
diff --git a/addons/mail/static/src/core/common/message_service.js b/addons/mail/static/src/core/common/message_service.js
index 4d6b424915d..935fcb1ca16 100644
--- a/addons/mail/static/src/core/common/message_service.js
+++ b/addons/mail/static/src/core/common/message_service.js
@@ -162,13 +162,13 @@ export class MessageService {
     }
 
     scheduledDateSimple(message) {
-        return message.scheduledDate.toLocaleString(DateTime.TIME_SIMPLE, {
+        return message.scheduledDate.toLocaleString(DateTime.TIME_24_SIMPLE, {
             locale: this.userService.lang?.replace("_", "-"),
         });
     }
 
     dateSimple(message) {
-        return message.datetime.toLocaleString(DateTime.TIME_SIMPLE, {
+        return message.datetime.toLocaleString(DateTime.TIME_24_SIMPLE, {
             locale: this.userService.lang?.replace("_", "-"),
         });
     }
diff --git a/addons/mail/static/tests/message/message_tests.js b/addons/mail/static/tests/message/message_tests.js
index ec948b33f52..4ec78263108 100644
--- a/addons/mail/static/tests/message/message_tests.js
+++ b/addons/mail/static/tests/message/message_tests.js
@@ -7,7 +7,12 @@ import { start } from "@mail/../tests/helpers/test_utils";
 
 import { deserializeDateTime } from "@web/core/l10n/dates";
 import { getOrigin } from "@web/core/utils/urls";
-import { makeDeferred, patchWithCleanup, triggerHotkey } from "@web/../tests/helpers/utils";
+import {
+    makeDeferred,
+    patchTimeZone,
+    patchWithCleanup,
+    triggerHotkey,
+} from "@web/../tests/helpers/utils";
 import { click, contains, insertText } from "@web/../tests/utils";
 import { SIZES, patchUiSize } from "../helpers/patch_ui_size";
 
@@ -671,6 +676,7 @@ QUnit.test("message comment of same author within 1min. should be squashed", asy
     // messages are squashed when "close", e.g. less than 1 minute has elapsed
     // from messages of same author and same thread. Note that this should
     // be working in non-mailboxes
+    patchTimeZone(0); // so it matches server timezone
     const pyEnv = await startServer();
     const channelId = pyEnv["discuss.channel"].create({ name: "general" });
     const partnerId = pyEnv["res.partner"].create({ name: "Demo" });
@@ -713,7 +719,7 @@ QUnit.test("message comment of same author within 1min. should be squashed", asy
     await contains(".o-mail-Message", {
         contains: [
             [".o-mail-Message-content", { text: "body2" }],
-            [".o-mail-Message-sidebar .o-mail-Message-date"],
+            [".o-mail-Message-sidebar .o-mail-Message-date", { text: "10:00" }],
         ],
     });
 });