diff --git a/osu.Game/Online/API/Requests/PostMessageRequest.cs b/osu.Game/Online/API/Requests/PostMessageRequest.cs
new file mode 100644
index 0000000000..52269d9fe8
--- /dev/null
+++ b/osu.Game/Online/API/Requests/PostMessageRequest.cs
@@ -0,0 +1,33 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using osu.Framework.Extensions;
+using osu.Framework.IO.Network;
+using osu.Game.Online.Chat;
+
+namespace osu.Game.Online.API.Requests
+{
+    public class PostMessageRequest : APIRequest<Message>
+    {
+        private readonly Message message;
+
+        public PostMessageRequest(Message message)
+        {
+            this.message = message;
+        }
+
+        protected override WebRequest CreateWebRequest()
+        {
+            var req = base.CreateWebRequest();
+
+            req.Method = HttpMethod.POST;
+            req.AddParameter(@"target_type", message.TargetType.GetDescription());
+            req.AddParameter(@"target_id", message.TargetId.ToString());
+            req.AddParameter(@"message", message.Content);
+
+            return req;
+        }
+
+        protected override string Target => @"chat/messages";
+    }
+}
\ No newline at end of file
diff --git a/osu.Game/Online/Chat/Channel.cs b/osu.Game/Online/Chat/Channel.cs
index d895b93336..04ebf0a389 100644
--- a/osu.Game/Online/Chat/Channel.cs
+++ b/osu.Game/Online/Chat/Channel.cs
@@ -3,7 +3,9 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Newtonsoft.Json;
+using osu.Framework.Lists;
 
 namespace osu.Game.Online.Chat
 {
@@ -21,7 +23,7 @@ namespace osu.Game.Online.Chat
         [JsonProperty(@"channel_id")]
         public int Id;
 
-        public List<Message> Messages = new List<Message>();
+        public SortedList<Message> Messages = new SortedList<Message>((m1, m2) => m1.Id.CompareTo(m2.Id));
 
         //internal bool Joined;
 
@@ -36,7 +38,10 @@ namespace osu.Game.Online.Chat
 
         public void AddNewMessages(IEnumerable<Message> messages)
         {
+            messages = messages.Except(Messages).ToList();
+
             Messages.AddRange(messages);
+
             purgeOldMessages();
 
             NewMessagesArrived?.Invoke(messages);
diff --git a/osu.Game/Online/Chat/Message.cs b/osu.Game/Online/Chat/Message.cs
index 5d781459e8..2404bbe109 100644
--- a/osu.Game/Online/Chat/Message.cs
+++ b/osu.Game/Online/Chat/Message.cs
@@ -11,7 +11,7 @@ namespace osu.Game.Online.Chat
     public class Message
     {
         [JsonProperty(@"message_id")]
-        public long Id;
+        public readonly long Id;
 
         //todo: this should be inside sender.
         [JsonProperty(@"user_id")]
@@ -36,6 +36,18 @@ namespace osu.Game.Online.Chat
         public Message()
         {
         }
+
+        public override bool Equals(object obj)
+        {
+            var objMessage = obj as Message;
+
+            return Id == objMessage?.Id;
+        }
+
+        public override int GetHashCode()
+        {
+            return Id.GetHashCode();
+        }
     }
 
     public enum TargetType
diff --git a/osu.Game/Overlays/ChatOverlay.cs b/osu.Game/Overlays/ChatOverlay.cs
index 2f1b21dd7b..5b9d30ee8e 100644
--- a/osu.Game/Overlays/ChatOverlay.cs
+++ b/osu.Game/Overlays/ChatOverlay.cs
@@ -89,25 +89,44 @@ namespace osu.Game.Overlays
             return false;
         }
 
-        private void postMessage(TextBox sender, bool newText)
+        private void postMessage(TextBox textbox, bool newText)
         {
-            var postText = sender.Text;
+            var postText = textbox.Text;
 
             if (!string.IsNullOrEmpty(postText) && api.LocalUser.Value != null)
             {
-                //todo: actually send to server
-                careChannels.FirstOrDefault()?.AddNewMessages(new[]
-                            {
-                                new Message
-                                {
-                                    User = api.LocalUser.Value,
-                                    Timestamp = DateTimeOffset.Now,
-                                    Content = postText
-                                }
-                            });
-            }
+                var currentChannel = careChannels.FirstOrDefault();
 
-            sender.Text = string.Empty;
+                if (currentChannel == null) return;
+
+                var message = new Message
+                {
+                    User = api.LocalUser.Value,
+                    Timestamp = DateTimeOffset.Now,
+                    TargetType = TargetType.Channel, //TODO: read this from currentChannel
+                    TargetId = currentChannel.Id,
+                    Content = postText
+                };
+
+                textbox.ReadOnly = true;
+                var req = new PostMessageRequest(message);
+
+                req.Failure += e =>
+                {
+                    textbox.FlashColour(Color4.Red, 1000);
+                    textbox.ReadOnly = false;
+                };
+
+                req.Success += m =>
+                {
+                    currentChannel.AddNewMessages(new[] { m });
+
+                    textbox.ReadOnly = false;
+                    textbox.Text = string.Empty;
+                };
+
+                api.Queue(req);
+            }
         }
 
         [BackgroundDependencyLoader]
@@ -137,7 +156,7 @@ namespace osu.Game.Overlays
             fetchReq.Success += delegate (List<Message> messages)
             {
                 var ids = messages.Where(m => m.TargetType == TargetType.Channel).Select(m => m.TargetId).Distinct();
-            
+
                 //batch messages per channel.
                 foreach (var id in ids)
                     careChannels.Find(c => c.Id == id)?.AddNewMessages(messages.Where(m => m.TargetId == id));
diff --git a/osu.Game/osu.Game.csproj b/osu.Game/osu.Game.csproj
index 8421f89058..6987776376 100644
--- a/osu.Game/osu.Game.csproj
+++ b/osu.Game/osu.Game.csproj
@@ -72,6 +72,7 @@
     <Compile Include="Audio\SampleInfo.cs" />
     <Compile Include="Beatmaps\Drawables\BeatmapBackgroundSprite.cs" />
     <Compile Include="Beatmaps\DifficultyCalculator.cs" />
+    <Compile Include="Online\API\Requests\PostMessageRequest.cs" />
     <Compile Include="Rulesets\Beatmaps\BeatmapConverter.cs" />
     <Compile Include="Rulesets\Beatmaps\BeatmapProcessor.cs" />
     <Compile Include="Beatmaps\Legacy\LegacyBeatmap.cs" />