diff --git a/addons/mail/static/src/js/services/mail_window_manager.js b/addons/mail/static/src/js/services/mail_window_manager.js
index 9cbb77e529d..c0e8a1e77d3 100644
--- a/addons/mail/static/src/js/services/mail_window_manager.js
+++ b/addons/mail/static/src/js/services/mail_window_manager.js
@@ -381,6 +381,7 @@ MailManager.include({
                     }
                 })
                 .on('click', '.o_thread_window_close', function (ev) {
+                    ev.preventDefault();
                     var threadID = $(ev.currentTarget).closest('.o_thread_window_header')
                                                       .data('thread-id');
                     var threadWindow = self._getHiddenThreadWindow(threadID);