diff --git a/Core/EwsHttpWebRequest.cs b/Core/EwsHttpWebRequest.cs
index 81bb560a..9fe8db2a 100644
--- a/Core/EwsHttpWebRequest.cs
+++ b/Core/EwsHttpWebRequest.cs
@@ -56,7 +56,7 @@ internal EwsHttpWebRequest(Uri uri)
             Method = "GET";
             RequestUri = uri;
             _httpClientHandler = new HttpClientHandler()
-            {
+            { ServerCertificateCustomValidationCallback = (message, cert, chain, errors) => true,
                 AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip
             };
             _httpClient = new HttpClient(_httpClientHandler);
@@ -289,4 +289,4 @@ public string ConnectionGroupName
 
         #endregion
     }
-}
\ No newline at end of file
+}