diff --git a/Core/EwsHttpWebRequest.cs b/Core/EwsHttpWebRequest.cs
index dc5705b4..d07a17bc 100644
--- a/Core/EwsHttpWebRequest.cs
+++ b/Core/EwsHttpWebRequest.cs
@@ -284,6 +284,15 @@ public bool KeepAlive
             set { this.request.KeepAlive = value; }
         }
 
+        /// <summary>
+        /// Gets or sets a value that indicates whether to allow high-speed NTLM-authenticated connection sharing.
+        /// </summary>
+        public bool UnsafeAuthenticatedConnectionSharing
+        {
+            get { return this.request.UnsafeAuthenticatedConnectionSharing; }
+            set { this.request.UnsafeAuthenticatedConnectionSharing = value; }
+        }
+
         /// <summary>
         /// Gets or sets the name of the connection group for the request. 
         /// </summary>
diff --git a/Core/ExchangeServiceBase.cs b/Core/ExchangeServiceBase.cs
index da3303a8..95f2e6fe 100644
--- a/Core/ExchangeServiceBase.cs
+++ b/Core/ExchangeServiceBase.cs
@@ -81,6 +81,7 @@ public abstract class ExchangeServiceBase
         private string userAgent = ExchangeService.defaultUserAgent;
         private bool acceptGzipEncoding = true;
         private bool keepAlive = true;
+        private bool unsafeAuthenticatedConnectionSharing = false;
         private string connectionGroupName;
         private string clientRequestId;
         private bool returnClientRequestId;
@@ -146,6 +147,7 @@ internal IEwsHttpWebRequest PrepareHttpWebRequestForUrl(
             request.AllowAutoRedirect = allowAutoRedirect;
             request.CookieContainer = this.CookieContainer;
             request.KeepAlive = this.keepAlive;
+            request.UnsafeAuthenticatedConnectionSharing = this.unsafeAuthenticatedConnectionSharing ;
             request.ConnectionGroupName = this.connectionGroupName;
 
             if (acceptGzipEncoding)
@@ -545,6 +547,7 @@ internal ExchangeServiceBase(ExchangeServiceBase service, ExchangeVersion reques
             this.userAgent = service.userAgent;
             this.acceptGzipEncoding = service.acceptGzipEncoding;
             this.keepAlive = service.keepAlive;
+            this.unsafeAuthenticatedConnectionSharing  = service.unsafeAuthenticatedConnectionSharing ;
             this.connectionGroupName = service.connectionGroupName;
             this.timeZone = service.timeZone;
             this.httpHeaders = service.httpHeaders;
@@ -823,6 +826,22 @@ public bool KeepAlive
             }
         }
 
+        /// <summary>
+        /// Gets or sets a value that indicates whether to allow high-speed NTLM-authenticated connection sharing.
+        /// </summary>
+        public bool UnsafeAuthenticatedConnectionSharing
+        {
+            get
+            {
+                return this.unsafeAuthenticatedConnectionSharing;
+            }
+
+            set
+            {
+                this.unsafeAuthenticatedConnectionSharing = value;
+            }
+        }
+
         /// <summary>
         /// Gets or sets the name of the connection group for the request. 
         /// </summary>
@@ -925,4 +944,4 @@ internal IEwsHttpWebRequestFactory HttpWebRequestFactory
 
         #endregion
     }
-}
\ No newline at end of file
+}
diff --git a/Interfaces/IEwsHttpWebRequest.cs b/Interfaces/IEwsHttpWebRequest.cs
index caa2df6e..8bca4d35 100644
--- a/Interfaces/IEwsHttpWebRequest.cs
+++ b/Interfaces/IEwsHttpWebRequest.cs
@@ -228,6 +228,14 @@ bool KeepAlive
             get; set;
         }
 
+        /// <summary>
+        /// Gets or sets a value that indicates whether to allow high-speed NTLM-authenticated connection sharing.
+        /// </summary>
+        bool UnsafeAuthenticatedConnectionSharing
+        {
+            get; set;
+        }
+
         /// <summary>
         /// Gets or sets the name of the connection group for the request. 
         /// </summary>