diff --git a/addons/mail/static/src/less/thread.less b/addons/mail/static/src/less/thread.less
index 7a9efa45731..058df431736 100644
--- a/addons/mail/static/src/less/thread.less
+++ b/addons/mail/static/src/less/thread.less
@@ -177,6 +177,7 @@
                     border-radius: 5px;
                     color: gray;
                     width: 300px;
+                    display: none;
                     opacity: 0;
                     position: absolute;
                     transition: opacity 0.5s;
@@ -186,6 +187,7 @@
                 }
 
                 .o_thread_tooltip:hover + .o_thread_tooltip_content {
+                    display: inline;
                     opacity: 1;
                 }
             }