diff --git a/addons/mail/static/src/js/composers/basic_composer.js b/addons/mail/static/src/js/composers/basic_composer.js
index bfd97028a2d..c2ca59ffa65 100644
--- a/addons/mail/static/src/js/composers/basic_composer.js
+++ b/addons/mail/static/src/js/composers/basic_composer.js
@@ -523,10 +523,9 @@ var BasicComposer = Widget.extend({
         clearTimeout(this._cannedTimeout);
         var self = this;
         this._preprocessMessage().then(function (message) {
-            self.trigger('post_message', message, function() {
-                self._clearComposerOnSend();
-                self.$input.focus();
-            });
+            self.trigger('post_message', message);
+            self._clearComposerOnSend();
+            self.$input.focus();
         });
     },
     /**
diff --git a/addons/mail/static/src/js/discuss.js b/addons/mail/static/src/js/discuss.js
index 0f2b7feff26..168e74cac4a 100644
--- a/addons/mail/static/src/js/discuss.js
+++ b/addons/mail/static/src/js/discuss.js
@@ -1490,9 +1490,8 @@ var Discuss = AbstractAction.extend({
     /**
      * @private
      * @param {Object} messageData
-     * @param {Function} callback
      */
-    _onPostMessage: function (messageData, callback) {
+    _onPostMessage: function (messageData) {
         var self = this;
         var options = {};
         if (this._selectedMessage) {
@@ -1513,7 +1512,6 @@ var Discuss = AbstractAction.extend({
                 } else {
                     self._threadWidget.scrollToBottom();
                 }
-                callback();
             });
     },
     /**
diff --git a/addons/mail/static/src/js/thread_windows/abstract_thread_window.js b/addons/mail/static/src/js/thread_windows/abstract_thread_window.js
index 27cb97e1f65..7ec1c214ef1 100644
--- a/addons/mail/static/src/js/thread_windows/abstract_thread_window.js
+++ b/addons/mail/static/src/js/thread_windows/abstract_thread_window.js
@@ -372,9 +372,8 @@ var AbstractThreadWindow = Widget.extend({
      *
      * @private
      * @param {Object} messageData
-     * @param {Function} callback
      */
-    _postMessage: function (messageData, callback) {
+    _postMessage: function (messageData) {
         var self = this;
         if (!this.hasThread()) {
             return;
@@ -382,7 +381,6 @@ var AbstractThreadWindow = Widget.extend({
         this._thread.postMessage(messageData)
             .then(function () {
                 self._threadWidget.scrollToBottom();
-                callback && callback();
             });
     },
     /**
diff --git a/addons/mail/static/tests/discuss_tests.js b/addons/mail/static/tests/discuss_tests.js
index bc31013ce52..8e8b663e83f 100644
--- a/addons/mail/static/tests/discuss_tests.js
+++ b/addons/mail/static/tests/discuss_tests.js
@@ -1733,57 +1733,6 @@ QUnit.test('receive channel message notification then delayed needaction notific
     discuss.destroy();
 });
 
-QUnit.test('input not cleared on unresolved message_post rpc', async function (assert) {
-    assert.expect(2);
-    // Promise to simulate late server response on message post
-    var messagePostPromise = testUtils.makeTestPromise();
-
-    this.data.initMessaging = {
-        channel_slots: {
-            channel_channel: [{
-                id: 1,
-                channel_type: "channel",
-                name: "general",
-            }],
-        },
-    };
-
-    var discuss = await createDiscuss({
-        id: 1,
-        context: {},
-        params: {},
-        data: this.data,
-        services: this.services,
-        mockRPC: function (route, args) {
-            if (args.method === 'message_post') {
-                return messagePostPromise;
-            }
-            return this._super.apply(this, arguments);
-        },
-    });
-
-    // Click on channel 'general'
-    var $general = discuss.$('.o_mail_discuss_sidebar').find('.o_mail_discuss_item[data-thread-id=1]');
-    await testUtils.dom.click($general);
-
-    // Type message
-    var $input = discuss.$('textarea.o_composer_text_field').first();
-    $input.focus();
-    $input.val('test message');
-
-    // Send message
-    await testUtils.fields.triggerKeydown($input, 'enter');
-    assert.strictEqual($input.val(), 'test message', "composer should not be cleared on send without server response");
-
-    // Simulate server response
-    messagePostPromise.resolve();
-
-    await testUtils.nextTick();
-    assert.strictEqual($input.val(), '', "composer should be cleared on send after server response");
-
-    discuss.destroy();
-});
-
 QUnit.test('messages marked as read move to "History" mailbox', async function (assert) {
     assert.expect(3);