diff --git a/addons/mail/static/src/core_ui/message.scss b/addons/mail/static/src/core_ui/message.scss
index f3f228cc0ff..4f60775c365 100644
--- a/addons/mail/static/src/core_ui/message.scss
+++ b/addons/mail/static/src/core_ui/message.scss
@@ -9,6 +9,10 @@
 .o-mail-Message-sidebar {
     flex-basis: $o-mail-Message-sidebarWidth;
     max-width: $o-mail-Message-sidebarWidth;
+
+    .o-mail-Message-date {
+        font-size: 0.75rem;
+    }
 }
 
 .o-mail-Message-avatarContainer {