diff --git a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Constants.cs b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Constants.cs
index d928f6e..d03a91d 100644
--- a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Constants.cs
+++ b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Constants.cs
@@ -71,6 +71,7 @@ namespace Acacia
 
         public const string ZPUSH_HEADER_GAB_NAME = "X-Push-GAB-Name";
         public const string ZPUSH_HEADER_CAPABILITIES = "X-Push-Capabilities";
+        public const string ZPUSH_HEADER_CLIENT_CAPABILITIES = "X-Push-Plugin-Capabilities";
         public const string ZPUSH_HEADER_PLUGIN = "X-Push-Plugin";
         public const string ZPUSH_HEADER_VERSION = "X-Z-Push-Version";
         
diff --git a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Features/Feature.cs b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Features/Feature.cs
index afc0d80..ac4608c 100644
--- a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Features/Feature.cs
+++ b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/Features/Feature.cs
@@ -63,6 +63,11 @@ namespace Acacia.Features
             get { return ThisAddIn.Instance.Application; }
         }
 
+        virtual public void GetCapabilities(ZPushCapabilities caps)
+        {
+            caps.Add(Name);
+        }
+
         #region Debug options
 
         public static string GetFeatureName(Type featureType)
diff --git a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/Connect/ZPushConnection.cs b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/Connect/ZPushConnection.cs
index e527ed8..3392646 100644
--- a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/Connect/ZPushConnection.cs
+++ b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/Connect/ZPushConnection.cs
@@ -280,7 +280,7 @@ namespace Acacia.ZPush.Connect
                 string url = string.Format(ACTIVESYNC_URL, _account.ServerURL, _account.DeviceId,
                     request.Command, _account.UserName, "WindowsOutlook");
 
-                // Parse the body
+                // Construct the body
                 WBXMLDocument doc = new WBXMLDocument();
                 doc.LoadXml(request.Body);
                 doc.VersionNumber = 1.3;
@@ -292,6 +292,9 @@ namespace Acacia.ZPush.Connect
                 {
                     Logger.Instance.Trace(this, "Sending request: {0} -> {1}", _account.ServerURL, doc.ToXMLString());
                     content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.ms-sync.wbxml");
+                    string caps = ZPushCapabilities.Client.ToString();
+                    Logger.Instance.Trace(this, "Sending request: {0} -> {1}: {2}", _account.ServerURL, caps, doc.ToXMLString());
+                    content.Headers.Add(Constants.ZPUSH_HEADER_CLIENT_CAPABILITIES, caps);
                     using (HttpResponseMessage response = _client.PostAsync(url, content, _cancel).Result)
                     {
                         return new Response(response);
diff --git a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/ZPushCapabilities.cs b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/ZPushCapabilities.cs
index 9792e08..742c9a6 100644
--- a/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/ZPushCapabilities.cs
+++ b/src/AcaciaZPushPlugin/AcaciaZPushPlugin/ZPush/ZPushCapabilities.cs
@@ -1,4 +1,6 @@
-/// Copyright 2016 Kopano b.v.
+
+using Acacia.Features;
+/// Copyright 2016 Kopano b.v.
 /// 
 /// This program is free software: you can redistribute it and/or modify
 /// it under the terms of the GNU Affero General Public License, version 3,
@@ -13,7 +15,6 @@
 /// along with this program.If not, see<http://www.gnu.org/licenses/>.
 /// 
 /// Consult LICENSE file for details
-
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
@@ -50,9 +51,26 @@ namespace Acacia.ZPush
             return _capabilities.Contains(capability);
         }
 
+        public void Add(string capability)
+        {
+            _capabilities.Add(capability);
+        }
+
         public override string ToString()
         {
             return string.Join(",", _capabilities);
         }
+
+        public static ZPushCapabilities Client
+        {
+            get
+            {
+                ZPushCapabilities caps = new ZPushCapabilities();
+                foreach (Feature feature in ThisAddIn.Instance.Features)
+                    feature.GetCapabilities(caps);
+
+                return caps;
+            }
+        }
     }
 }