diff --git a/mail_archives/static/src/js/archives.js b/mail_archives/static/src/js/archives.js
index 912523a..fab77c9 100644
--- a/mail_archives/static/src/js/archives.js
+++ b/mail_archives/static/src/js/archives.js
@@ -16,6 +16,15 @@ var web_client = require('web.web_client');
 var _lt = core._lt;
 //-------------------------------------------------------------------------------
 
+var ChatAction = core.action_registry.get('mail.chat.instant_messaging');
+ChatAction.include({
+    get_thread_rendering_options: function (messages) {
+        var options = this._super.apply(this, arguments);
+        options.display_subject = options.display_subject || this.channel.id === "channel_archive";
+        return options;
+    }
+});
+
 // Inherit class and override methods
 base_obj.MailTools.include({
     get_properties: function(msg){
diff --git a/mail_sent/static/src/js/sent.js b/mail_sent/static/src/js/sent.js
index 681ae22..40be2c3 100644
--- a/mail_sent/static/src/js/sent.js
+++ b/mail_sent/static/src/js/sent.js
@@ -27,6 +27,11 @@ ChatAction.include({
                 .find('.o_mail_chat_button_new_message')
                 .toggle(channel.id === "channel_inbox" || channel.id === "channel_sent");
         });
+    },
+    get_thread_rendering_options: function (messages) {
+        var options = this._super.apply(this, arguments);
+        options.display_subject = options.display_subject || this.channel.id === "channel_sent";
+        return options;
     }
 });