diff --git a/addons/mail/static/src/js/services/chat_manager.js b/addons/mail/static/src/js/services/chat_manager.js
index 8ae45486e16..ec8e4c64299 100644
--- a/addons/mail/static/src/js/services/chat_manager.js
+++ b/addons/mail/static/src/js/services/chat_manager.js
@@ -1582,16 +1582,21 @@ var ChatManager =  AbstractService.extend({
                 message.is_starred = data.starred;
                 if (!message.is_starred) {
                     self._removeMessageFromChannel("channel_starred", message);
-                    self.starredCounter--;
                 } else {
                     self._addToCache(message, []);
                     var channelStarred = self.getChannel('channel_starred');
                     channelStarred.cache = _.pick(channelStarred.cache, "[]");
-                    self.starredCounter++;
                 }
                 self.chatBus.trigger('update_message', message);
             }
         });
+
+        if (data.starred) { // increase starred counter if message is marked as star
+            this.starredCounter += data.message_ids.length;
+        } else { // decrease starred counter if message is remove from star if unstar_all then it will set to 0.
+            this.starredCounter -= data.message_ids.length;
+        }
+
         this.chatBus.trigger('update_starred', this.starredCounter);
     },
     /**
diff --git a/addons/mail/static/tests/discuss_tests.js b/addons/mail/static/tests/discuss_tests.js
index 862b643abb4..af600ef3087 100644
--- a/addons/mail/static/tests/discuss_tests.js
+++ b/addons/mail/static/tests/discuss_tests.js
@@ -375,5 +375,109 @@ QUnit.test('older messages are loaded on scroll', function (assert) {
     });
 });
 
+QUnit.test('"Unstar all" button should reset the starred counter', function (assert) {
+    assert.expect(2);
+    var done = assert.async();
+
+    var bus = new Bus();
+    var BusService = createBusService(bus);
+    var msgData = [];
+    _.each(_.range(1, 41), function (num) {
+        msgData.push({
+                id: num,
+                body: "<p>test" + num + "</p>",
+                author_id: ["1", "Me"],
+                channel_ids: [1],
+                starred: true,
+                starred_partner_ids: [1],
+            }
+        );
+    });
+
+    this.data = {
+        initMessaging: {
+            channel_slots: {
+                channel_channel: [{
+                    id: 1,
+                    channel_type: "channel",
+                    name: "general",
+                }],
+            },
+            starred_counter: msgData.length,
+        },
+        'mail.message': {
+            fields: {
+                body: {
+                    string: "Contents",
+                    type: 'html',
+                },
+                author_id: {
+                    string: "Author",
+                    relation: 'res.partner',
+                },
+                channel_ids: {
+                    string: "Channels",
+                    type: 'many2many',
+                    relation: 'mail.channel',
+                },
+                starred: {
+                    string: "Starred",
+                    type: 'boolean',
+                },
+                needaction: {
+                  string: "Need Action",
+                  type: 'boolean',
+              },
+              starred_partner_ids: {
+                  string: "partner ids",
+                  type: 'integer',
+              }
+            },
+            records: msgData,
+        },
+    };
+
+    createDiscuss({
+        id: 1,
+        context: {},
+        params: {},
+        data: this.data,
+        services: [ChatManager, BusService],
+        mockRPC: function (route, args) {
+            if (args.method === 'unstar_all') {
+                var data = {
+                    message_ids: _.range(1, 41),
+                    starred: false,
+                    type: 'toggle_star',
+                };
+                var notification = [[false, 'res.partner'], data];
+                bus.trigger('notification', [notification]);
+                return $.when(42);
+            }
+            return this._super.apply(this, arguments);
+        },
+        session: {partner_id: 1},
+    })
+    .then(function (discuss) {
+        var $starred = discuss.$('.o_mail_chat_sidebar').find('.o_mail_chat_title_starred');
+        var $starredCounter = $('.o_mail_chat_title_starred > .o_mail_sidebar_needaction');
+
+        // Go to Starred channel
+        $starred.click();
+        // Test Initial Value
+        assert.strictEqual($starredCounter.text().trim(), "40", "40 messages should be starred");
+
+        // Unstar all and wait 'update_starred'
+        $('.o_control_panel .o_mail_chat_button_unstar_all').click();
+        $starredCounter = $('.o_mail_chat_title_starred > .o_mail_sidebar_needaction');
+        assert.strictEqual($starredCounter.text().trim(), "0",
+            "All messages should be unstarred");
+
+        discuss.destroy();
+        done();
+    });
+});
+
+
 });
 });
diff --git a/addons/mail/static/tests/helpers/mock_server.js b/addons/mail/static/tests/helpers/mock_server.js
index 01ce78221f0..98c5a4eb375 100644
--- a/addons/mail/static/tests/helpers/mock_server.js
+++ b/addons/mail/static/tests/helpers/mock_server.js
@@ -39,6 +39,21 @@ MockServer.include({
             'menu_id': false,
         });
     },
+
+    /**
+     * Simulate the 'message_fetch' Python method
+     *
+     * @return {Object}
+     */
+    _mockMessageFetch: function (args) {
+        args.kwargs.offset = Math.max(this.data['mail.message'].records.length - args.kwargs.limit, 0);
+
+        return this._mockSearchRead('mail.message', [
+            args.args[0],
+            _.keys(this.data['mail.message'].fields),
+        ], args.kwargs);
+    },
+
     /**
      * @override
      */
@@ -47,7 +62,7 @@ MockServer.include({
             return $.when(this._mockInitMessaging(args));
         }
         if (args.method === 'message_fetch') {
-            return $.when([]);
+            return $.when(this._mockMessageFetch(args));
         }
         if (args.method === 'channel_fetch_listeners') {
             return $.when([]);
diff --git a/addons/mail/static/tests/helpers/test_utils.js b/addons/mail/static/tests/helpers/test_utils.js
index cd933bc2483..f7292c7a67e 100644
--- a/addons/mail/static/tests/helpers/test_utils.js
+++ b/addons/mail/static/tests/helpers/test_utils.js
@@ -5,6 +5,7 @@ var Discuss = require('mail.chat_discuss');
 
 var AbstractService = require('web.AbstractService');
 var Bus = require('web.Bus');
+var ControlPanel = require('web.ControlPanel');
 var testUtils = require('web.test_utils');
 var Widget = require('web.Widget');
 
@@ -75,6 +76,8 @@ function createDiscuss(params) {
     var discuss = new Discuss(parent, params);
     discuss.set_cp_bus(new Widget());
     var selector = params.debug ? 'body' : '#qunit-fixture';
+    var controlPanel = new ControlPanel(parent);
+    controlPanel.appendTo($(selector));
     discuss.appendTo($(selector));
 
     // override 'destroy' of discuss so that it calls 'destroy' on the parent
@@ -86,6 +89,9 @@ function createDiscuss(params) {
         parent.destroy();
     };
 
+    // link the view to the control panel
+    discuss.set_cp_bus(controlPanel.get_bus());
+
     return discuss.call('chat_manager', 'isReady').then(function () {
         return discuss;
     });