diff --git a/chat_box/models.py b/chat_box/models.py
index 9ede6db..00a76a2 100644
--- a/chat_box/models.py
+++ b/chat_box/models.py
@@ -66,7 +66,6 @@ class Message(models.Model):
     )
 
     def save(self, *args, **kwargs):
-        new_message = self.id
         self.body = self.body.strip()
         super(Message, self).save(*args, **kwargs)
 
diff --git a/chat_box/views.py b/chat_box/views.py
index b01994a..34dcfe5 100644
--- a/chat_box/views.py
+++ b/chat_box/views.py
@@ -174,19 +174,46 @@ def mute_message(request):
     return JsonResponse(ret)
 
 
+def check_valid_message(request, room):
+    if not room and len(request.POST["body"]) > 200:
+        return False
+
+    if not can_access_room(request, room) or request.profile.mute:
+        return False
+
+    last_msg = Message.objects.filter(room=room).first()
+    if (
+        last_msg
+        and last_msg.author == request.profile
+        and last_msg.body == request.POST["body"].strip()
+    ):
+        return False
+
+    if not room:
+        four_last_msg = Message.objects.filter(room=room).order_by("-id")[:4]
+        if len(four_last_msg) >= 4:
+            same_author = all(msg.author == request.profile for msg in four_last_msg)
+            time_diff = timezone.now() - four_last_msg[3].time
+            if same_author and time_diff.total_seconds() < 300:
+                return False
+
+    return True
+
+
 @login_required
 def post_message(request):
     ret = {"msg": "posted"}
+
     if request.method != "POST":
         return HttpResponseBadRequest()
-    if len(request.POST["body"]) > 5000:
+    if len(request.POST["body"]) > 5000 or len(request.POST["body"].strip()) == 0:
         return HttpResponseBadRequest()
 
     room = None
     if request.POST["room"]:
         room = Room.objects.get(id=request.POST["room"])
 
-    if not can_access_room(request, room) or request.profile.mute:
+    if not check_valid_message(request, room):
         return HttpResponseBadRequest()
 
     new_message = Message(author=request.profile, body=request.POST["body"], room=room)
@@ -229,9 +256,7 @@ def post_message(request):
 
 
 def can_access_room(request, room):
-    return (
-        not room or room.user_one == request.profile or room.user_two == request.profile
-    )
+    return not room or room.contain(request.profile)
 
 
 @login_required
@@ -247,7 +272,7 @@ def chat_message_ajax(request):
     try:
         message = Message.objects.filter(hidden=False).get(id=message_id)
         room = message.room
-        if room and not room.contain(request.profile):
+        if not can_access_room(request, room):
             return HttpResponse("Unauthorized", status=401)
     except Message.DoesNotExist:
         return HttpResponseBadRequest()
@@ -278,7 +303,7 @@ def update_last_seen(request, **kwargs):
     except Room.DoesNotExist:
         return HttpResponseBadRequest()
 
-    if room and not room.contain(profile):
+    if not can_access_room(request, room):
         return HttpResponseBadRequest()
 
     user_room, _ = UserRoom.objects.get_or_create(user=profile, room=room)
diff --git a/resources/chatbox.scss b/resources/chatbox.scss
index 2e47cf6..f45244b 100644
--- a/resources/chatbox.scss
+++ b/resources/chatbox.scss
@@ -99,6 +99,7 @@
 }
 .info-pic {
     height: 95%;
+    width: 100%;
 }
 
 .info-name {
diff --git a/templates/chat/chat.html b/templates/chat/chat.html
index 8ad9e16..fce740f 100644
--- a/templates/chat/chat.html
+++ b/templates/chat/chat.html
@@ -88,7 +88,7 @@
           </ul>
         </div>
         <div id="chat-input-container">
-          <textarea maxlength="5000" id="chat-input" placeholder="{{_('Enter your message')}}"></textarea>
+          <textarea maxlength="{{5000 if room else 200}}" id="chat-input" placeholder="{{_('Enter your message')}}"></textarea>
           <div class="chat-input-icon" id="emoji-button" href="#" title="{{_('Emoji')}}"><i class="icofont-slightly-smile"></i>
           </div>
           <div class="chat-input-icon" id="submit-button">
diff --git a/templates/chat/chat_js.html b/templates/chat/chat_js.html
index a843e5a..e259b87 100644
--- a/templates/chat/chat_js.html
+++ b/templates/chat/chat_js.html
@@ -36,8 +36,7 @@
           $('#chat-log').prepend(data);
         }
 
-        register_time($('.time-with-rel'));
-        merge_authors();
+        postProcessMessages();
 
         if (!refresh_html) {
           $chat_box.scrollTop(scrollTopOfBottom($chat_box) - lastMsgPos);
@@ -51,6 +50,13 @@
     })
   }
 
+  function postProcessMessages() {
+    register_time($('.time-with-rel'));
+    MathJax.typeset();
+    populateCopyButton();
+    merge_authors();
+  }
+
   function scrollTopOfBottom(container) {
     return container[0].scrollHeight - container.innerHeight()
   }
@@ -111,10 +117,7 @@
 
     $('#chat-log').append($data);
     $('#chat-box').scrollTop($('#chat-box')[0].scrollHeight);
-    register_time($('.time-with-rel'));
-    MathJax.typeset();
-    populateCopyButton();
-    merge_authors();
+    postProcessMessages();
   }
 
   function add_new_message(message, room, is_self_author) {
@@ -167,11 +170,8 @@
           else {
             add_new_message(message, room, true);
           }
-          MathJax.typeset();
-          populateCopyButton();
-          register_time($('.time-with-rel'));
           remove_unread_current_user();
-          merge_authors();
+          postProcessMessages();
         },
         error: function (data) {
           console.log('Fail to check message');
@@ -245,6 +245,9 @@
         $.post("{{ url('post_chat_message') }}", message)
           .fail(function(res) {
           console.log('Fail to send message');
+          var $body = $('#message-text-'+ message.tmp_id);
+          $body.css('text-decoration', 'line-through');
+          $body.css('background', 'red');
         })
           .done(function(res, status) {
           $('#empty_msg').hide();
@@ -307,8 +310,10 @@
       load_next_page(null, true);
       update_last_seen();
       refresh_status(true);
-      $('#chat-input').focus();
+
       show_right_panel();
+      $('#chat-input').focus();
+      $('#chat-input').val('').trigger('input');
     }
     window.lock_click_space = true;
     if (encrypted_user) {
@@ -318,6 +323,7 @@
         window.other_user_id = data.other_user_id;
         color_selected_room();
         callback();
+        $('#chat-input').attr('maxlength', 5000);
       })
         .fail(function() {
         console.log('Fail to get_or_create_room');
@@ -328,6 +334,7 @@
       window.other_user_id = '';
       color_selected_room();
       callback();
+      $('#chat-input').attr('maxlength', 200);
     }
     window.lock_click_space = false;
   }
diff --git a/templates/chat/message.html b/templates/chat/message.html
index ba20db9..ad6a004 100644
--- a/templates/chat/message.html
+++ b/templates/chat/message.html
@@ -23,7 +23,7 @@
             {{_('Mute')}}
           </a>
         {% endif %}
-        <div class="message-text message-text-other">
+        <div class="message-text message-text-other" id="message-text-{{ message.id }}">
           {{message.body|markdown(lazy_load=False)|reference|str|safe }}
         </div>
       </div>
diff --git a/templates/chat/message_list.html b/templates/chat/message_list.html
index 3dcdc97..3f7e188 100644
--- a/templates/chat/message_list.html
+++ b/templates/chat/message_list.html
@@ -6,4 +6,5 @@
   {% endfor %}
 {% else %}
   <center id="empty_msg">{{_('You are connect now. Say something to start the conversation.')}}</center>
-{% endif %}
\ No newline at end of file
+{% endif %}
+