diff --git a/addons/mail/static/src/components/message/message.scss b/addons/mail/static/src/components/message/message.scss
index 8fe3d7a2219..c131fe24aba 100644
--- a/addons/mail/static/src/components/message/message.scss
+++ b/addons/mail/static/src/components/message/message.scss
@@ -56,6 +56,11 @@
     > p:last-of-type {
         margin-bottom: 0;
     }
+
+    img {
+        max-width: 100%;
+        height: auto;
+    }
 }
 
 .o_Message_core {